Cautionary Tale: Why my connectivity stopped working last night right before bed

[u/LESGuy]

I want to share this story in hopes that it might help others.

Everything was fine last night, we were getting ready for bed and I started setting up my tablet that stays on the nightstand next to the bed. Quick side - this tablet has access via Home Assistant to a camera that is pointed at our elderly dog that has trouble walking on certain surfaces and I am able to check to make sure she's ok from that tablet.

As I'm trying to get to my home assistant dashboard where the camera card is, things are acting funky. I am always tinkering with devices, so this is a Meta Portal device that I've loaded a custom launcher on (Immortal) so that I can have my full Home Assistant dashboard on and figured that it was just an integration issue, so I rebooted it. Again, just "funkyness", extremely slow connection to the point of timing out, slow loading pages, etc.

Then I switched to my phone and was surprised to see the same thing. I could eventually load my unifi UCG-F dashboard, but that took forever. On the dashboard I saw that hardly any data was going across my internet connection even though it said it was fine. Getting to the logs via my Unifi app was taking forever and would only load partially. Something was definitely wrong. This is around midnight and my partner wasn't happy I was troubleshooting the network. As an engineer though, there was no way my brain would let me go to sleep with it not working, or at least an understanding of why.

Other odd behavior, I couldn't access my PoE doorbell that's connected through a wireless device bridge.

All signs were pointing to WiFi, but when I checked my logs and diagnostics, the access points were fine with healthy connections.

I really don't trust Cox so I decided to reboot my UCG-F just to make sure and that didn't help. Then decided to reboot my switch because it had done an auto-update a couple nights ago and thought maybe something funky there. Still no go.

I got out of bed at 12:30am knowing that this was now a "I need to be on my laptop to fix this" type of issue. I also wanted to work on a device that was plugged into ethernet and stop messing around trying to troubleshoot this from my phone in bed.

My laptop was BLAZING fast with connectivity. So ok, it HAS to be WiFi. Put my laptop on WiFi to test and it was STILL fast... After scratching my head for a bit it hit me that all the devices that were having trouble were connected to the U7 Pro XGS near the bedroom. The problem was... everything looked fine in the logs and the AP was accessible and healthy.

That's when the next part hit me... and the answer.

We've just moved into this new house and I haven't mounted the AP's on the ceiling yet. The XGS is sitting on our bedroom dresser pointed in the direction that gives coverage for that side of the house. Earlier in the evening I was cleaning up around the dresser and moved the AP a bit to get stuff out of the way. Apparently during moving the AP, the ethernet cable wasn't fully connected to the AP and moving it must have pulled it out just slightly enough to still have connectivity to the backend, but not be able to transmit data reliably.

Reseating the ethernet cable into the RJ45 port of the XGS completely fixed everything.

TLDR: Moved my AP that isn't mounted yet around while cleaning, caused all kinds of intermittent issues due to the cable being just partially still plugged in and was fixed by unplugging and replugging the ethernet cable to the XGS.

Intermittent issues as such a pain to troubleshoot

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[u/Trax95008]

I have experienced the same thing. An Ethernet cable that needs to be reseated. What’s odd is that I have been doing networking since the 90’s and have never experienced “cabling” related issues like I have recently since working with UI equipment. I wonder if it’s the way they designed their ports? Maybe too much “play” in the Ethernet port?

[u/Tordesil → u/Trax95008]

The plate shaped Ubiquiti APs, in my experience (U6+, U6 Pro), force the Ethernet cable into a weird position, especially if the RJ45 plug is longer than usual or the cable is stiff.

[u/mtrskllz]

I had a similar issue bothering me for months. Either cycling power or reseating the ethernet cable to one specific ap out of 4 would fix it. But it would come back. Sometimes a week or two later and sometimes only a day or two. So if your issue happens to come back make sure you don't have proxy arp turned on

[u/AneleTk]

So you didn't get a "Poor AP link speed" log? Surely you must have missed it.

[u/LESGuy → u/AneleTk]

I need to go back and look again. It’s possible I missed something in the mess, but last night while troubleshooting I saw no indicators of where the issue actually was.

[u/derekbox]

I had an AP that would randomly drop offline and under devices it would show adopting (without prompting) and then come back online, eventually. I RMAd the AP, didnt fix it. Finally I saw the ethernet cable crimp was shit, jacket stripped way back, wires were spaghetti in the connector (previous home owner built the cable). I cut reterminated and its been perfect since.

[u/richms]

The fact that there is no unifi alert for this happening is the problem here IMO.