I've been using pfsense for years without this issue and I've made no recent changes to the config but a couple weeks ago my wife started complaining about briefly not being able to "use the internet" and I didn't believe her cause I would be streaming or something at the time and by the time I tested her devices, it was fine. But I experienced it yesterday and today, DNS_PROBE_FINISHED_NXDOMAIN will flash on the browser. This happens on my main LAN and VLAN's and resolves itself in anywhere between 30 seconds to 10 minutes and then I experience no issues at any other time (that i can tell). I can use other aspects of the internet and can even ping google.com from the command line with low latency. And then it fixes itself! What gives? I don't even know where to begin to troubleshoot this but my hunch is that the DNS server is being overloaded briefly by something? Not sure how reasonable a theory this is or how to track it down but it's the best I got right now...
I use DNS Resolver with basically default settings (enabled on all interefaces, DNSSEC enabled, Register DHCP, Static DHCP, OpenVPN all enabled), all the devices are pointed to the pfsense box for their DNS Server. In the DNS Server(s) on the mainpage I have listed:
127.0.0.1
8.8.8.8
208.67.220.220
8.8.4.4
208.67.222.222
Any advice extremely appreciated!