Dappnode.local intermittently showing "403 Forbidden" or "unable to connect"

Fresh install of dappnode 0.2.75 on custom hardware (Intel i7, 16gb RAM).

No wifi card installed so I’m using the local proxy for initial config. About 9 out of 10 times that I try to connect to http://dappnode.local I get either a “403 forbidden” error or just “unable to connect”/“connection refused”. I’ve been able to connect and begin the setup but then randomly I’ll get the 403 error or a “connect lost” screen.

I’ve confirmed that the PC is still connected and I can ping its local IP.

Any help appreciated.