Troubleshooting unRAID becoming inaccessible at tower.local (only by IP)

I've just started using unRAID, and I've run an issue pretty consistently where the server stops being available at tower.local and is only available by IP address. I start off using the web GUI at http://tower.local and it works fine, but then after less than an hour, it stops responding. If I instead access it by IP address it works fine and unRAID was clearly running the whole time.

The same issue happens when I try accessing it via ssh. It works at first, but then stops working. In case it was specific to the Mac, I've also tried on my iPhone with the same results (works, then stops working). When it stops working in one place (browser, terminal, iphone), it also stops working everywhere else at the same time.

I haven't yet tried from a non-Apple device as my one non-unRAID PC is off most of the time.

I've looked in the logs on my Mac and on the unRAID server, but neither seem to have anything logged around the time that this happens.

I haven't noticed anything consistent with when this happens except that I've been navigating around the web UI. Restarting unRAID fixes it.

Any suggestions on how to troubleshoot this?