Ubuntu 16 KVM VPS (GigE Uplink)
Cloudflare DNS Upstream
All default blacklists plus all these:
https://discourse.pi-hole.net/t/update-the-best-blocking-lists-for-the-pi-hole-alternative-dns-servers-2019/13620
Using single static IP on the VPS (no DHCP). Enabled DNSSEC and left default " Listen only on interface eth0" setting checked.
Problem: seems like Pi-hole will work for a while, then sort of disconnect. I use iOS app, AdGuard Pro to add my custom Pi-hole DNS server (which is basically the main VPS IP address). I would use or try another app like DNS Cloak but there is no option to add your own custom DNS.
I use AdGuard Pro since you can add your own DNS and it works for both LTE and WiFi. So currently my only fix is to disable and re-enable the DNS manually via AdGuard app.
Example is that absolutely nothing works. Internet stops dead cold until I either toggle Wifi on/off but usually I have to toggle the Pi-hole DNS on/off via the AdGuard app.