Huawei CPE hirouter.net https login problem

Morning guys

I'm getting a security warning when trying to access the hirouter.net login page

Looking it's a well documented issue - but I can't seem to find a solution!?

I've added an exception for the time being, but does anyone here know a fix to this problem?

(PC clock is correct time, I've tried different browsers, different machines, tried the IP directly, and I really don't fancy calling Three tech support....)

TIA

Probably just a self-signed certificate error that can be safely ignored.