Home Assistant stops waiting for an offline Modbus device before finishing startup. An unplugged or unreachable meter, inverter or other device could keep the final startup phase waiting until its timeout; four reports measured about 318 seconds.
Franck Nijhof moves connection attempts and regular polling into the background without changing their timing. Removing or disabling an entity also cancels its pending wait, so an absent device does not leave work running for a deleted entity.