Use dnsmasq for DNS
As the name already implies, dnsmasq is not a full-fledged DNS server. If you want a real, recursive DNS resolver, consider using unbound instead.
dnsmasq is available on SailfishOS chum. You 1st need to add the 3rd-party-repo, afterwards running
devel-su pkcon refresh && pkcon install dnsmasq will install it.
Disable your current DNS handler
Permanently run dnsmasq on boot
devel-su systemctl enable --now dnsmasq to enable it permanently & start it now.