Ubuntu 24.04.1 LTS apt update / upgrade running very slowly when NextDNS is turned on

This is strange and I can't figure out why it's happening.

I use NextDNS at my router level to cover my network, and when I have the network set up that way apt update/upgrade works at normal speed.

When I configure resolved per NextDNS instructions like this:

Use the following in /etc/systemd/resolved.conf: (or use nextDNS cli interface program)

[Resolve]
DNS=45.90.28.0#
xxxxx
.dns.nextdns.io
DNS=2a07:a8c0::#
xxxxx
.dns.nextdns.io
DNS=45.90.30.0#
xxxxx
.dns.nextdns.io
DNS=2a07:a8c1::#
xxxxx
.dns.nextdns.io
DNSOverTLS=yes

so that I can differentiate my linux box in NextDNS logs and take advantage of DoT, apt update/upgrade runs very, very slowly.

However everything else internet wise works fine - -speetest show close to 1 gig speed no matter what my nextdns settings are.

This is annoying but not life changing. I'd rather have DoT active and slow apt update/upgrade than the opposite.

Is there any work around for this?

thanks.