The request was aborted: Could not create SSL/TLS secure channel.

Running v18 EAP1:

 

Have simple firewall rule, which allows traffic to the Internet, there are NO security features setup on XG in the rule, only a NAT:

 

I have a Playstation on the LAN and also a server that sends out to PushOver, now the Playstation cannot connect to the playstation network, and Pushover is being stopped, I get this from ex. Pushover:

"The request was aborted: Could not create SSL/TLS secure channel."

I have disabled SSL inspection also on XG.

 

Some services work, but others don't on the network.

 

I found out, that if I go and enable this:

 

 

Everything works again!

What could be wrong here?

With 17.5.8 I had the same rule, with no security enabled, no issues here.

The sometimes I can disable the proxy again, and it keeps working, just as if it hold the connection.

Would make sense if the SSL inspection on/off was broken, and it was still on, but I cannot understand why SSL/TLS is broken, with it all disabled :-)