Weird, I could not get to https://2degrees.nz if I used their DNS servers. Had no problems with other services, just theirs.
I could if I VPN'd into work.
I have a fixed IP4 address at home.
It complained about certificate issues too (could not be validated)
I manually changed the DNS on my Fritzbox adding both IP4/IP6 DNS for CloudFlare DNS and all is working normally , though I think CloudFlare DNS is faster