So two days ago, I upgraded my main workstation to Ubuntu 23.10; a few little issues (mostly related to my own scripts), but nothing serious. Yet.
On the following day, my smart TV box started misbehaving. It couldn’t see any of the videos NFS mounted from my workstation, ITVX threw up a website error (this should have been a clue), but Youtube worked fine (which showed that the network was working fine).
So I did the obvious thing and started checking the NFS parameters to see if anything had changed. Nothing definite but on the way I noticed that the TV box wasn’t getting an IPv4 address from the dhcp server; IPv6 was working fine but some services don’t work on an IPv6 network.
I foolishly assumed that the TV box had stopped requesting addresses via dhcp – backed by the dhcp logs which showed no requests had been logged since the previous day. Set a static address, and everything sprang into life (except for ITVX who seem to have decided that only approved TV boxes should be allowed to run their code).
Later that same day, I upgraded a switch which failed to come back (“Failed to adopt”) which caused a daisy-chained wireless access point to disappear (“Failed to adopt”). And then a little while later, a second unconnected wireless access point also disappeared.
After a few reboots of the switch (and access points), I finally checked the dhcp server and found that its root filesystem had become ‘read-only’. But that wasn’t the end of the misdiagnosis …
I assumed that the SD card in my dhcp server (a tiny ARM box) was fried, so made arrangements to backup the contents, buy a couple of replacements, and try a spare (which was broken). After the spare turned out to be broken, I ran fsck on the root filesystem of the original and a whole bunch of errors were fixed.
Re-installed into the ARM box, and everything sprang to life again.
I guess the moral of the story is that you should check the basic services before diving into making assumptions.