Config Settings NextDNS App on Ubuntu

I have now installed the NextDNS App, after having had endless troubles with Stubby.

But I am having the same issues with the NextDNS App - either it resolves VERY slowly, or it works for a short while and then hangs itself up after a while - especially whilst downloading files or downloading emails.

Can someone see an error in my config?

report-client-info false
discovery-dns 
auto-activate true
timeout 5s
control /var/run/nextdns.sock
cache-size 10MB
bogus-priv true
use-hosts true
config "******"
cache-max-age 12h0m0s
max-ttl 5s
hardened-privacy false
setup-router false
listen localhost:53
log-queries false
detect-captive-portals false

THANKS!