Note, at time of writing, 6.10.3 is current and this happened on all 6.10.X releases thus far.
I previously had crashing issues at least once every 72 hours with 6.9 using docker containers w/ static IPs.
To combat that at the time I created a docker-specific VLAN for the few containers that needed static IPs.
Fast forward to 6.10.X and the release of the ipvlan mode which was supposed to help people with this issue.
I went ahead and removed my VLAN and swapped docker to ipvlan mode and everything works great.
That is, up until I do my weekly CA appdata backup (via Squid's excellent plugin, of course)
When running it would finish and then restart docker containers but my entire system would actually lose outside access to the internet, and I have no idea why.
The network/internet access would stay down until I rebooted, or if left alone long enough would eventually restore itself after 5-10 hours or so.
I was able to seemingly track this down to docker service itself, since stopping docker service restored network connectivity immediately. Very weird...
I wasn't able to troubleshoot/chase this further as I rely on this server far too much for my day to day life at this point.
I have since reverted back to macvlan mode with a docker-specific VLAN and so far my issue has not recurred.
here are two threads where I report the problems but wasn't able to get anywhere with it.
I figure submitting this as an official bug report may help get it some attention, as it's certainly a weird issue that I couldn't narrow down...
I have also marked this as urgent because it's a pretty MAJOR bug to have everything lose internet access.