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Pieter-Jan Nefkens

@pjnef.bsky.social
159 followers 130 following 61 posts

IT & network consultant, engineer, CiscoPress author, #ciscoChampion, cisco, network & security adept. Sadly also LongCovid :-(

PostsRepliesMedia
Reposted by Pieter-Jan Nefkens
Saganism @sagan.bsky.social · 14/08/2026
41 years ago, Carl Sagan gave a clear and elegant explanation of the science behind global warming.
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Reposted by Pieter-Jan Nefkens
Tom Hollingsworth @networkingnerd.net · 28/01/2026
Guess what's new for 2026? We're streaming live on Youtube! Check out the stream here: www.youtube.com/techfieldday
youtube.com
Tech Field Day
Tech Field Day is now part of The Futurum Group. Our events bring together innovative IT product vendors and independent thought leaders to share information and opinions in a presentation and discuss...
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Pieter-Jan Nefkens @pjnef.bsky.social · 31/12/2025
No wonder i have an asthma attack.. the fine dust levels are skyrocketing in my backyard due to fireworks.
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Pieter-Jan Nefkens @pjnef.bsky.social · 30/12/2025
To be honest, with #longcovid & #severeasthma i am not really looking forward to new year’s eve. It will be a day where #pacing and taking rest will be extremely difficult, a crash is to be expected as my available points (cronocarecoach.com ) remain the same but the day is longer. #chronicillness
cronocarecoach.com
Crono Care Coach - Energy Management for Chronic Conditions
Living with a chronic condition means learning to manage limited energy. Crono Care Coach helps you track how you're doing daily. Privacy-first, data stays on your phone
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Pieter-Jan Nefkens @pjnef.bsky.social · 22/12/2025
crono care coach is now live in the apple app store. Register your triggers and activities with points, score & color each day An app (built by someone with longcovid) that helps you with #pacing and #energymanagement. Built for any #chronicillness such as #severeasthma #longcovid #mecfs
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Pieter-Jan Nefkens @pjnef.bsky.social · 19/12/2025
This share from a linkedIn post has a lot of meaning to me. An app that i have been working on for the past years that contains the things that helped me with #longcovid #severeasthma & #pacing is now live in the app store. It helped me getting to where i am today. www.linkedin.com/posts/pieter...
linkedin.com
Take control of your chronic condition | Pieter-Jan Nefkens
The post I am writing today has a lot of meaning to me. I have completed one of my year ambitions and I am incredibly proud of the result. Because Apple has approved the App that I have created, calle...
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Pieter-Jan Nefkens @pjnef.bsky.social · 16/12/2025
I’ve come across plenty, dhcp server, mail, web, database, domain controllers.. all my servers & serving containers have static ipv6
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Pieter-Jan Nefkens @pjnef.bsky.social · 16/12/2025
Oh this is all in the network config and operating servers. No app config . That is all dns
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Pieter-Jan Nefkens @pjnef.bsky.social · 15/12/2025
Though if you enter v6 addresses frequently enough, it will get into your muscle memory.. and use logic numbering for servers. That prefix will become muscle memory. Really
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Pieter-Jan Nefkens @pjnef.bsky.social · 16/11/2025
Agreed. Yet at the same time i must say that google’s focus for ads means that the creditability of google results has dropped significantly. Must say the research option gives good decent results
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Pieter-Jan Nefkens @pjnef.bsky.social · 29/09/2025
It has been almost 3 years since i last saw this view. It will be mine for the coming 8 weeks of #severeasthma rehab in the swiss mountains. 🤞 for a good period to get back up on my feet and refind balance #longcovid
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Reposted by Pieter-Jan Nefkens
ME/CFS San Diego @mecfssd.bsky.social · 24/06/2025
🧬 The largest-ever ME/CFS biological study finds consistent blood abnormalities tied to inflammation, insulin resistance & liver dysfunction—not explained by inactivity. 🔬 Brings us closer to a diagnostic test. 📰 www.ed.ac.uk/news/scale-o... 📄 www.embopress.org/doi/full/10....
ed.ac.uk
Scale of how ME/CFS affects blood revealed
People with ME/CFS have significant differences in their blood compared with healthy individuals, a new study reveals, suggesting a path towards more reliable diagnosis of the long-term debilitating i...
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Reposted by Pieter-Jan Nefkens
Peter Jones @petergjones.bsky.social · 17/06/2025
Hey #CiscoChampion folks, I've started a list for Cisco Champions(current and emeritus) and Champions-adjacent people (e.g., Tech Field Day, Cisco Champions Champions) Ping me if you want to get added. bsky.app/profile/did:...
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Pieter-Jan Nefkens @pjnef.bsky.social · 13/05/2025
2️⃣
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Reposted by Pieter-Jan Nefkens
Jonas Seufert @joseuf.bsky.social · 10/05/2025
Mehrere Hundert Menschen bei ME/CFS #Liegenddemo in Leipzig. Betroffene haben Redebeiträge geschrieben, fordern Anerkennung, Unterstützung, Forschung. #longcovid #curemecfs
Demotransparent mit der Aufschrift #LiegendDemoDemoschild mit der Aufschrift Tine vermisst ihre Arbeit, Tine vermisst Freunde treffen, Tine vermisst die Welt verbessern, wir vermissen Tine, Forschung ist unsere Hoffnung Mehrere hundert Menschen liegen auf dem Leipziger Marktplatz stellevertretend für ME/CFS Betroffene
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Reposted by Pieter-Jan Nefkens
Guus @guusontheinternet.bsky.social · 10/05/2025
“Het is nu tijd voor een inhaalslag, voor biomedisch onderzoek, voor meer kennis van zaken. De overheid en universiteiten moeten daarom flink gaan investeren in onderzoek naar PAIS.” #PAIS #MECVS #LongCovid
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Pieter-Jan Nefkens @pjnef.bsky.social · 06/05/2025
This is in line with other dutch research from jan ‘24 that showed that the mitochrondia in the muscle cells (and presumably all cells) do not function properly.
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Reposted by Pieter-Jan Nefkens
Tom Kindlon @tomkindlon.bsky.social · 06/05/2025
Important new research from the Netherlands: Skeletal muscle properties in long COVID and ME/CFS differ from those induced by bed rest www.medrxiv.org/content/10.1... #LongCovid #MEcfs
Abstract
Patients with long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) suffer from a reduced exercise capacity, skeletal muscle abnormalities and post-exertional malaise (PEM), where symptoms worsen with cognitive or physical exertion. PEM often results in avoidance of physical activity, resulting in a lower aerobic fitness, which may contribute to skeletal muscle abnormalities. Here, we compared whole-body exercise responses and skeletal muscle adaptations after strict 60-day bed rest in healthy people with those in patients with long COVID and ME/CFS, and healthy age- and sex-matched controls. Bed rest altered the respiratory and cardiovascular responses to (sub)maximal exercise, while patients exhibited respiratory alterations only at submaximal exercise. Bed rest caused muscle atrophy, and the reduced oxidative phosphorylation related to reductions in maximal oxygen uptake. Patients with long COVID and ME/CFS did not have muscle atrophy, but had less capillaries and a more glycolytic fibers, none of which were associated with maximal oxygen uptake. While the whole-body aerobic capacity is similar following bed rest compared to patients, the skeletal muscle characteristics differed, suggesting that physical inactivity alone does not explain the lower exercise capacity in long COVID and ME/CFS
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Reposted by Pieter-Jan Nefkens
Scott Hogg @scotthogg.bsky.social · 24/04/2025
Hogg Networking Relaunches and Rebrands with Renewed Emphasis on Providing #IPv6 Training and Consulting Services www.einpresswire.com/article/8059...
einpresswire.com
Hogg Networking Relaunches and Rebrands with Renewed Emphasis on Providing IPv6 Training and Consulting Services
Hogg Networking is proud to announce the re-launching of our company with a focus on providing large enterprises with IPv6 training and technical guidance.
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Pieter-Jan Nefkens @pjnef.bsky.social · 24/04/2025
Living with a chronic illness is tough. Today 3 colleagues threw a retirement party. it was planned months ahead,it allowed me to pal around it and have enough room tomorrow to recover.And then the weather changed, triggering my asthma, so i had to cancel something i was looking forward to.
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Pieter-Jan Nefkens @pjnef.bsky.social · 17/03/2025
So recognizable. We are often really our own worst enemy
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Reposted by Pieter-Jan Nefkens
Arjantim @arjantim.bsky.social · 11/02/2025
The @cisco.com Agile Services Networking looks to simplify the Networking Architecture for the Enterprise, what do think? @techfieldday.com #TFDx #CiscoLiveEMEA
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Reposted by Pieter-Jan Nefkens
Arjantim @arjantim.bsky.social · 11/02/2025
So we're almost going live with the first part of the @techfieldday.com @ciscoliveemea.bsky.social @cisco.com Go beyond is the first slide 🙂 See you live here: techfieldday.com/event/clemea... #CiscoLiveEMEA #TFDx
linkedin.com
Tech Field Day on LinkedIn: Tech Field Day Extra at Cisco Live EMEA 2025
Tech Field Day Extra at Cisco Live EMEA 2025
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Reposted by Pieter-Jan Nefkens
Tech Field Day @techfieldday.com · 05/02/2025
We may only be a few weeks into 2025 but we're ready to bring you more great content! We will once more be broadcasting live from Amsterdam as we kick off Tech Field Day Extra #TFDx at #CiscoLiveEMEA 2025. There are lots of exciting technology announcements that you're not going to want to miss.
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Pieter-Jan Nefkens @pjnef.bsky.social · 11/02/2025
In less then 10 minutes we'll be live with #TFDx at #CiscoLiveEMEA. Thunderbolt launch and directly afterwards Firewalling in the DC Switching, eg Smart Switches. Join us at the livestream: techfieldday.com/event/clemea...
techfieldday.com
Tech Field Day Extra at Cisco Live EMEA 2025 - Tech Field Day
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Pieter-Jan Nefkens @pjnef.bsky.social · 11/02/2025
I am honored to be one of the delegates at TechFieldDay Extra. #TFDx at #CiscoLiveEMEA will start the livestream at 13:00 CET. Join me today on a number of very interesting hashtag#datacenter topics like: #Cisco SmartSwitches & Nexus HyperFabric
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Pieter-Jan Nefkens @pjnef.bsky.social · 03/02/2025
Found a neat trick on iPhone that I just shared: nefkens.net/securing-app...
nefkens.net
Securing app access on your iPhone - Pieter-Jan Nefkens
A short howto explaining how to put an extra layer of protection to any iOS app.
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Pieter-Jan Nefkens @pjnef.bsky.social · 25/01/2025
Finally took the time to write the blog post on #DigitalSovereignty and #SovereignCloud , explaining the term, its concepts and models. nefkens.net/sovereign-cl...
nefkens.net
Digital Sovereignty/Sovereign cloud explained - Pieter-Jan Nefkens
Digital sovereignty or sovereign cloud are becoming buzzwords. In this post I'll explain what digital sovereignty and sovereign cloud is about.
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Pieter-Jan Nefkens @pjnef.bsky.social · 16/01/2025
Well it is also a good way to effectively disable that isp forced wifi on 160MHz from ruining your channel plan ;-)
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Pieter-Jan Nefkens @pjnef.bsky.social · 13/01/2025
Honored that i have been invited for @techfieldday.com extra at #CLEUR . Looking forward to learn and write about it
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Reposted by Pieter-Jan Nefkens
Daniel Dib @ddib.bsky.social · 13/01/2025
Have you heard about #mDNS? It's one of those protocols that go under the radar, but that can really wreak havoc on your network if you don't manage it. While mainly used for consumer stuff, expect to see it in your network. It uses link local multicast so gets flooded at L2.
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Pieter-Jan Nefkens @pjnef.bsky.social · 13/01/2025
And dont forget #mDNS uses #IPv6 too..
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Pieter-Jan Nefkens @pjnef.bsky.social · 04/01/2025
And some pics leaving gotheburg.. yesterday evening we saw venus near the moon, dont know which planet this is
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Pieter-Jan Nefkens @pjnef.bsky.social · 04/01/2025
Driving back to the ferry from a winter break resulted in beautiful pictures (and driving with -20 celcius)..
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Pieter-Jan Nefkens @pjnef.bsky.social · 24/12/2024
Happy holidays everyone!
media.tenor.com
snoopy is blowing a bell on christmas eve .
ALT: snoopy is blowing a bell on christmas eve .
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Pieter-Jan Nefkens @pjnef.bsky.social · 16/12/2024
Puff pastry
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Pieter-Jan Nefkens @pjnef.bsky.social · 14/12/2024
I’m so much not a happy camper at the moment. Iphone said service of battery, made appointment, heard had to pay whilst apple support app said not (applecare) and spending the afternoon restoring from a wipe that wasnt necessary (and lost all signal chat along the way). Never going back to amac
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Pieter-Jan Nefkens @pjnef.bsky.social · 13/12/2024
Can you provide the rto/rpo times for each application that is run on the infra, so we can determine the rto/rpo for the infra Do you have tco calculations for current infra? Do you know the business cost for 1hr downtime?
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Pieter-Jan Nefkens @pjnef.bsky.social · 09/12/2024
Yet they only function with clear direction which is again clear leadership. And the q to me is if this would also work in managed services (eg existing services) and not only go-and-build-x statements (which is more like create a controlled startup)
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Reposted by Pieter-Jan Nefkens
Matt Massicotte @massicotte.org · 30/11/2024
Ok, it's time for another one of these "Swift concurrency step-by-step" posts. It explores working with types that are not Sendable. All based around reading a model from some data store. www.massicotte.org/step-by-step...
massicotte.org
Concurrency Step-by-Step: Reading from Storage
Not too long ago, I was re-reading an “introductory” post I wrote. Honestly, I could barely make it though. I guess a big part of that is that my own defintion of “introduction” when it comes to concu...
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Reposted by Pieter-Jan Nefkens
IPv6 Army @ipv6.army · 29/11/2024
Multihoming in #IPv6 is still difficult. blog.ipspace.net/2024/11/ipv6...
blog.ipspace.net
IPv6 Support for Multiple Routers and Multiple Interfaces « ipSpace.net blog
Fernando Gont published an Individual Internet Draft (meaning it hasn’t been adopted by any IETF WG yet) describing the Problem Statement about IPv6 Support for Multiple Routers and Multiple Interface...
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Pieter-Jan Nefkens @pjnef.bsky.social · 22/11/2024
Now that there’s a hobby desk in the living room where i can leave stuuf, i’ve been able to pickup my hobby a bit more. Planking the hull step by step.
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Pieter-Jan Nefkens @pjnef.bsky.social · 19/11/2024
I have a 1gbps up/down fiber connection, running full dualstack #ipv4 and #ipv6
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Nick Buraglio @forwardingplane.net · 17/11/2024
Shamelessly lifted from someone else #ipv6
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Reposted by Pieter-Jan Nefkens
MacRumors.com @macrumors.bsky.social · 16/11/2024
Apple Acknowledges iCloud Notes Disappearing and Explains How to Fix
macrumors.com
Apple Acknowledges iCloud Notes Disappearing and Explains How to Fix
Earlier this month, we reported about some iPhone users temporarily losing all of their notes in the Notes app after accepting Apple's updated iCloud terms and conditions. Apple has now indirectly acknowledged this issue in a new support document that…
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Pieter-Jan Nefkens @pjnef.bsky.social · 14/11/2024
So much for apple solving watchOS 11 battery drain issues. Still happens on 11.1 :-(
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Pieter-Jan Nefkens @pjnef.bsky.social · 12/11/2024
I did a thing! I replaced the strings on my spanish guitar for the first time ever!
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Pieter-Jan Nefkens @pjnef.bsky.social · 08/11/2024
Would this work? www.pyxll.com/docs/introdu...
pyxll.com
Python in Excel with PyXLL, the Python Excel Add-in
Run Python in Excel with PyXLL. Write fully featured, fast, Excel add-ins in Python.
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Pieter-Jan Nefkens @pjnef.bsky.social · 08/11/2024
Postgresql is the oracle database in opensource world (not in cost but jn quality)
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Pieter-Jan Nefkens @pjnef.bsky.social · 08/11/2024
And dont forget the sheer energy consumption that will remove all orgs sustainability achievements of past years. AI is a trendbreaker to getting more energy-efficient datacenters of past decade(s)
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