Logs indicate that the connections are being forcibly closed by the gateway.
Operation 'CEM: Connect' failed.
Protocol: HTTPS
Original host: servername.domain.xyz:443
Real host: servername.domain.xyz:443
Path: /
Connection id: 123.45678
Communication profile id: {GUID of Communication Profile}
Throttling: 0 0 0
Error type: TLS Handshake error
Error code: An existing connection was forcibly closed by the remote host (0x80072746)
Error note: The connection was closed by the server during TLS handshake, check the System Event Log on the server for SCHANNEL errors
Release: 8.x
There were two NAT rules with a single IP address going to different servers
Fix the NAT rules.