Interface Behavior with invalid TLS Cert for 'Server certificate verification'

Hello,

I was just trying to get to the bottom of a TLS config - we have an interface with a TLS config that has had 'Server certificate verification' set to 'On', however the cert file specified either did not exist or contained a cert that was expired.

Does anyone know what the behavior is for this typically? I would expect this to not allow traffic on the interface, however this has been working fine for a few years now with an invalid cert specified for 'Server certificate verification' and set to 'On'.