“I Understand the Risks“, “Add Exception“, “Confirm Security Exception” – but they still don’t let you procede – they think for you it is better, not to “Permanently store this exception“, so please uncheck that box, and then “Confirm Security Exception“.
A while ago I wasn’t really aware of that checkbox, and I did not try toggling it and confirming again, and I just thought: how bad, Firefox does not let me access that web-page anymore. They are right in a sense, that confirming such an untrusted exception for ever is a bad thing. But in my case (connecting to a NAS on my LAN) it makes perfect sense. But how would they know? I don’t want to got through the hassle of creating certificates for my NAS-s.