Mac Mini M1 keeps disappearing from home network

I'm trying to run a Mac Mini M1 as a media server. I control it with Apple Remote (for music) and VLC remote (for video). Normally, no screen is connected, but I can screen share from a MacBook Air, if I need to access the drive directly. However, the machine keeps vanishing from my list of available devices, meaning that Remote can't see its library and I can't connect to it from my laptop. This happens at least every day and often several times per day. There is no obvious pattern to the disconnection. Nothing is being changed in the network settings and all the sharing preferences are correct - and if that weren't the case, the setup wouldn't work at all, which it does, but only ever for a couple of hours. All my other devices are recognised as usual on the LAN and when I connect a screen and keyboard to troubleshoot the M1, it's clear that the WiFi connection is also working normally. I'm running Sonoma and all my software is updated automatically, but the problem predated Sonoma anyway. This is all immensely frustrating.