btinternet.com/btopenworld.com suddenly not working on EM Client

Hi all, I imported an outlook account yesterday for somebody, a btopenworld email address. All worked perfectly until around 8pm when it could no longer connect. 

It appears that either EM client has had an update or BT servers have because it was working, and now it wont. I have tried btinternet, btopenworld, ssl, 993 etc etc. The settings work perfectly on outlook and thunderbird (on the same machine) but if i try importing those accounts into em client it no longer works. 
SO i thought it might be the machine, i tried setting up on a different computer on a different internet connection and still the same result. They, for what ever reason are no longer compatible with each other. Help!!

“An attempt to connect to email@btinternet.com failed. this could be caused by a temporary server unavailablilty or incorrect settings. do you want to check the settings?”

All variations have been tried and this is NOT a settings issue. 

Hi,

All eM Client updates are done manually, not in the background so I’m afraid this issue must be server related or antivirus related. It is possible an antivirus might’ve had an update which caused it to block eM Client. Can you please try disabling antivirus/firewall to see if the issue persists?