Simkl tracker plugin - Emby - Can't login using usbx URL

After installing Simkl Tracker plugin & restarting the Emby app, I tried to login with Simkl tracker plugin. It throwed this error.

Error:

Solution that worked for me:
I connected to my usbx vpn and logged into my Emby via usbx's local IP address & port (found in network tab of emby server dashboard)

Then I successfully logged in to my Simkl account using the Simkl Tracker plugin.

I wonder why it throws error via usbx URL, because I didn't face any issue while connecting to my Trakt account via Trakt plugin in Emby.