M1 MacBook Air can't access shared folders on other Macs

My M1 MacBook Air (updated to Big Sur 11.0.1 first thing) can't access shared folders on other Macs on my network, specifically my Mac mini running Mojave. I'm posting this in the hardware-specific section because another MBA (x86) running a fresh install of 11.0.1 *can* access shared folders on the mini.

I am trying to connect using "Connect to Server" and have tried both the hostname and IP address of the mini. I can ping the IP address, but not the hostname. That reads to me like Bonjour is having issues (though that doesn't address the failure by IP).

All three Macs are setup with the same username/password and the x86 Macs can see each other. This seems like functionality too basic not to be working.

Anyone else encountered this? Find a solution?