"Log in to Domain" malfunctioning

[Snowmon]

Hi

We have 4 servers linked to Expand, 2 being Windows machines.
On both of them the same thing happens when trying to 'login to domain': nothing.
It changes the URL to the relevant server but the page just stays blank.

The URL changes to this-

https://cp2.snowballeffect.net:8443/...n_cant_connect

https://cp4.snowballeffect.net:8443/...n_cant_connect

It says error in the URL but there's no error on screen, it's just a white page.
This used to work in the past. If anyone can help with this it would be much appreciated.
If any additional info is needed please let me know!

[Zer0eXe]

If you still get this ->> Unable to access the remote service: connecting to remote session failed. Contact your system administrator for support.
1.Check in "Administrator information" - Allow multiple sessions under administrator's login - check this to allow.
OR
2.if you trying to get from expand to plesk server(or from plesk server to Cmailer) and get white screen and in address tab "failure_redirect_url" - uncheck in the same panel "Prevent users from working with the control panel until interface screens are completely loaded" and save it suppose to solve it.