To prevent that, set a short lease time (like 2-5 minutes) in both the DHCP service and in the settings for passthrough.
Then the device will re-request the DHCP lease soon, and it will notice that it has changed.
When the DHCP service has a long lease time (like 1 day) that is no way for the TRB500 to tell the device “hey, the user has changed my setup and now you need to re-request the lease” except for unplugging of the cable.
(well, in reality the TRB500 could simulate the unplugging of the cable, and I have requested that as a new feature some weeks ago, but at the moment that is not possible)