Ultra-Low Latency Issue

Romain Cointepas Appreciate the reply! So far, in my brief testing, I only notice this on my home network. When connecting to 5G/LTE things seem to work fine. It seems like this issue happens when I wake my iPhone up and start browsing. I’m using eero’s for my home network with Spectrum internet.  Any other ideas? Thanks. 

Romain Cointepas I turned it off and was able to successfully go to that URL in my browser and also ping it.

Romain Cointepas One more thing. I have NextDNS DNS IP’s from a configuration in my NextDNS account also used on my router. Could there be a conflict of some sort when used on the router (using linked IP) and also being used on my iPhone with Ultra-Low turned on?

Romain Cointepas Yes, using the app Net Analyzer. I’ve posted this on Reddit (https://reddit.com/r/nextdns/comments/kyxw0o/ultralow_latency_issue/) and it seems like a person or two may be seeing the same issue as well. Like I said, turning Ultra-Low Latency OFF fixes the issue so I’ll leave it off for now.

Romain Cointepas I turned Ultra-Low to ON in the app, waited about 8 minutes until DNS requests stopped responding and then went to the Net Analyzer app and successfully pinged 1.1.1.1 and 8.8.8.8. Toggling Ultra-Low OFF to ON or OFF made DNS to start responding again. Also, it seems if you wait a period of time (45 second to a minute) DNS will start responding again without toggling Ultra-Low or turning it OFF. However, in another 5-10 minutes it will happen all over again with DNS not responding. 

Romain Cointepas Do you have no configuration IPv6 addresses that I could also add?

Romain Cointepas Thanks for those. Yea, I attempted to only use IPv6 DNS but the eero app wouldn’t let me leave IPv4 primary blank and therefore couldn’t “save” the DNS configuration on the eero router. 

Romain Cointepas OK, so I’m not sure how much this will help but...

NextDNS: 1 issue of DNS randomly stopped responding.
Cloudflare: No issues. 
ISP: No issues.

I’m really not sure what to think. Maybe since I’m using both IPv4 & IPv6 NextDNS DNS addresses on my router if conflicts with the app/Ultra-Low? I suppose I could turn off IPv6 on my router to check.

Romain Cointepas I'll try that soon. One more quick thing... I woke my iPhone up and attempted to go to a website in Safari. DNS wasn't responding (Ultra-Low ON), but I had my MacBook on my lap at the same time, which is running NextDNS macOS app and is ENABLED, so I opened Safari and DNS was responding normally. I'm not sure if that rules anything out (maybe rules out the router?), but thought I'd let you know.

Romain Cointepas I turned off IPv6 on my router and have yet to see this issue happen where DNS randomly stops responding with Ultra-Low ON. Maybe this is due to the app switching from IPv4 to IPv6 DNS servers with a delay in between the switch? Is that probable? Any other thoughts? Does this help?

Romain Cointepas I did notice it again, but this time it took several hours for it to happen/me to notice. 
 

Here are the outputs...

{"Status":0,"TC":false,"RD":true,"RA":true,"AD":true,"CD":false,"Question":[{"name":"dns.nextdns.io.","type":28}],"Answer":[{"name":"dns.nextdns.io.","type":5,"TTL":284,"data":"steering.nextdns.io."},{"name":"steering.nextdns.io.","type":28,"TTL":60,"data":"2602:ff62:181:2d6::"},{"name":"steering.nextdns.io.","type":28,"TTL":60,"data":"2001:19f0:5c01:1ebc:5400:2ff:fece:28ed"}],"Additional":[{"name":".","type":41,"TTL":0,"data":"\n;; OPT PSEUDOSECTION:\n; EDNS: version 0; flags: ; udp: 1220"}]}

{"Status":0,"TC":false,"RD":true,"RA":true,"AD":true,"CD":false,"Question":[{"name":"dns.nextdns.io.","type":65}],"Answer":[{"name":"dns.nextdns.io.","type":5,"TTL":258,"data":"steering.nextdns.io."},{"name":"steering.nextdns.io.","type":65,"TTL":60,"data":"1 dns1.steering.nextdns.io. alpn=\"h2\" ipv4hint=\"191.96.51.196\" ipv6hint=\"2602:ff62:181:2d6::\""},{"name":"steering.nextdns.io.","type":65,"TTL":60,"data":"1 dns2.steering.nextdns.io. alpn=\"h2\" ipv4hint=\"45.76.16.236\" ipv6hint=\"2001:19f0:5c01:1ebc:5400:2ff:fece:28ed\""},{"name":"steering.nextdns.io.","type":65,"TTL":60,"data":"2 anycast.dns1.nextdns.io. alpn=\"h2\" ipv4hint=\"45.90.28.0\" ipv6hint=\"2a07:a8c0::\""},{"name":"steering.nextdns.io.","type":65,"TTL":60,"data":"3 anycast.dns2.nextdns.io. alpn=\"h2\" ipv4hint=\"45.90.30.0\" ipv6hint=\"2a07:a8c1::\""}],"Additional":[{"name":".","type":41,"TTL":0,"data":"\n;; OPT PSEUDOSECTION:\n; EDNS: version 0; flags: ; udp: 1220"}]}