--instance=N sets PPSSPP_ID, so each instance gets its own 127.0.0.N address
and MAC; headless left it at 0, which made its address 127.0.0.0.
--realtime keeps emulated time from running ahead of the wall clock. Only
display flips paced headless, and a test that doesn't draw never flips, so
two instances waiting for each other over the network timed out at once.
--adhoc-server runs the built-in ad hoc server.
Tools/adhoc_multi.py runs a multi-console pspautotest (X_host, X_client,
X_client2, ...) on one instance per role, with the built-in server or, with
--relay, a local aemu_postoffice in relay mode.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>