I have an ER605 router connected to a TL-SG2008P switch, also using an OC300 hardware controller. I'm also using two access points, one designated the "Living Room AP" and connected directly to the switch, and a second designated the "Office AP" and connected wirelessly to the first over mesh. 

In the last few weeks (with no configuration changes on my end) I've started having connectivity issues where the internet connection for a device will drop out entirely while the device remains connected to the wireless network. The connection usually comes back after a minute or two (but sometimes takes longer). While the internet isn't working, I'm still able to connect wirelessly to the hardware controller and change settings or check logs, but there aren't any logs that seem to appear concurrently with the loss of internet connection. As far as my modem is concerned, it claims to retain its internet connection the entire time and shows as connected when I log in to my service provider to check on that end. The controller software also continues to indicate that the connection from the router to the internet is "online" for the duration of these outages. 

It's not clear to me exactly where the problem lies, but the controller logs show two things happening consistently without any input on my end:

1. The Office AP IP/subnet mask will reset to 0.0.0.0/0.0.0.0, and then within a few seconds correct back to 10.75.1.5/255.255.255.0 (which is what it's supposed to be). In the logs, it looks like this (most recent entry first):

However, this issue dates back as far as my logs go (August 18), and I haven't been noticing connectivity problems as a network user that far back. 

2. At seemingly entirely separate times (hours away from the issue above), there are logs that say the Living Room AP was connected to the switch, and then disconnected usually under 10 minutes later. In the logs it looks like this:

The same thing is happening with devices that connect to the WAN:

However, sometimes the logs will go a long time and show none of these connect/disconnect issues. What's strange to me is that if you look at the logs, the logged events are not the same time apart as the log suggests - for example, it says the Galaxy-S23-Ultra was connected for 13h15m, but the logs show the connection happening 5 minutes before the disconnection. 

So far I've made sure all the firmware is updated, rebooted all devices, and "forgot" and re-provisioned both APs. I can't find any mention of similar issues anywhere in the community. Any ideas for what could be happening?