I feel really stupid, but a router restart ended up fixing it. That was weird that I was only having issues with the one connection but it seems to be working. Thanks for your time.
Yeah, turning off IPv6 and restarting my router seemed to allow a ping to the HA server. I have no clue what triggered it all, but after a thousand reboots of everything electronic, I seem to be online now.
I am having the same issues here. Restarting the router does in fact fix the issue, however, this is happening frequently, sometimes multiple times a day. I have disabled IPv6, Home assistant is on a static IP Address, and both are on a UPS so I do not think its a power issue.
I have a similar issue with ESPHome devices becoming unavailable in Home Assistant even though I can still access them through ESPHome / their IP Address. Just like with local access to Home Assistant, restarting the router generally gets them to talk nicely with Home Assistant again.
I am wondering after reading through this if I maybe just have a router issue and its time to replace it? I wanted to get some additional insight / opinions before I go spend money though.