LinuxServer Changes:
Update to v4. Env vars EXTERNAL_URL, EXTERNAL_SERVER_PORT and AUTOJOIN_PASSWORD are deprecated and no longer have any effect. Env vars AUTOJOIN_ENABLED and AUTOJOIN_ROOM are still working but will be removed in the future in favor of synclounge's built-in var autojoin__room. If you are reverse proxying, do not forget to update your proxy settings (here and here) as the server port and addresses are changed.
Remote Changes:
Updating to 5.1.57