NextDNS Down

I have been using nextdns for almost a long time using opnSense as my router with unbound with DNSSEC enabled It has been working well but today, nothing would work. No DNS could be resolved on any device within the network - all devices use pfsense for DNS resolution. I have not changed any settings in the router for many months.

Disabling NextDNS and enabling any of the other DNS Providers e.g. google, cloudflare, quad9 with the same settings set instantly resolve dns.

opnSense reports the error "can't find domain.abc: Server Failed", 

Also if I turn DNSSEC off then NextDNS magicly springs back to life.  Have had DNSSEC enabled all the time I've been using NextDNS, until today.