@lrh

Does the device controller page show 192.168.100.1 for the router controller?  Can you ping the router controller? There have been some issues with ER605 router not liking any IP address except for the defaut 192.168.0.1.  Have you to tried connecting directly to the port on the controller?  May want to try a factory reset (by holding reset button while returning power and continue to hold it for 10 seconds) on the OC200, flashing firmware, and loading your backed-up configuration.    

@1207 Thanks for your quick response! To be clear this isn't the router's internal web UI (that one shows up but is blocked from logging in since my system is managed by the OC200 controller), but the OC200's web UI that I am trying to access internally (through its direct IP address) versus from the cloud. I can access it through Omada Cloud, but not from inside my home network through its internal IP address.

I can ping it fine, no errors, but the web UI errors throwing the ERR_CONNECTION_REFUSED error.

My router is the TL-ER7206 if that matters.

Thanks!