The peer range shouldn’t be your LAN, it should be a new network range, just for WireGaurd. Make sure that the server running Immich is part of the WireGaurd network.
My phone and laptop see three networks: the internet, the lan (192.168.1.0/24, typically) and WireGaurd (10.30.0.0/16). I can anonymize and share my WireGaurd config if that would help.