Pi Hole no longer resolving for network clients

[Ackis]

The issue I am facing:

Pi Hole no longer resolves for network clients. It resolves for itself, however anything using it as its DNS server no longer can access domain names. I'm still able to access IP addresses and changing the DNS server from my Pi Hole to 1.1.1.1 works, allowing me to browse the internet again.

There's a bunch of lines like this in my log files, but from searching it seems safe to ignore them.
FATAL: Trying to access upstream ID -1, but maximum is 1024

Details about my system:

Pi Hole is acting as the DHCP server for IP4/6 as well as the DNS server. I'm using an EdgeRouter Max as well, which may or may not be configured properly (things work).

Log is uploded here: https://tricorder.pi-hole.net/2b6u352tcc
There's a few errors in the log, but nothing that seems to point to my problem.

When I used nslookup originally on a client machine, everything would resolve to 192.168.0.200 (IP of my DNS server), now I'm getting:

nslookup google.com 192.168.0.200
Server:  pasula-dns-pi.ackis.duckdns.org
Address:  192.168.0.200

*** pasula-dns-pi.ackis.duckdns.org can't find google.com: Server failed

What I have changed since installing Pi-hole:

I had 3 or 4 power outages last night.

[DanSchaper]

Might be unrelated but your IPv6 configuration is broken. You don't seem to actually have IPv6 enabled on the Pi-hole host and you're trying to use IPv6 upstreams:

*** [ DIAGNOSING ]: Networking
[✓] IPv4 address(es) bound to the eth0 interface:
   192.168.0.200/24 matches the IP found in /etc/pihole/setupVars.conf

[✓] IPv6 address(es) bound to the eth0 interface:
   fe80::f4ea:4d4b:d3d4:8d39 does not match the IP found in /etc/pihole/setupVars.conf (https://discourse.pi-hole.net/t/use-ipv6-ula-addresses-for-pi-hole/2127)

   ^ Please note that you may have more than one IP address listed.
   As long as one of them is green, and it matches what is in /etc/pihole/setupVars.conf, there is no need for concern.

   The link to the FAQ is for an issue that sometimes occurs when the IPv6 address changes, which is why we check for it.

*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] 6.load13.biz is 0.0.0.0 via localhost (127.0.0.1)
[✓] 6.load13.biz is 0.0.0.0 via Pi-hole (192.168.0.200)
[✓] doubleclick.com is 142.251.33.110 via a remote, public DNS server (8.8.8.8)

*** [ DIAGNOSING ]: Name resolution (IPv6) using a random blocked domain and a known ad-serving domain
[✓] www.here-adult-games1.com is :: via localhost (::1)
[✗] Failed to resolve www.here-adult-games1.com via Pi-hole (2604:3d09:<GUA REDACT>fb34)
[✗] Failed to resolve doubleclick.com via a remote, public DNS server (2001:4860:4860::8888)

    IPV4_ADDRESS=192.168.0.200/24
    IPV6_ADDRESS=2604:3d09:<GUA REDACT>fb34
    PIHOLE_DNS_1=1.1.1.1
    PIHOLE_DNS_2=1.0.0.1
    PIHOLE_DNS_3=2606:4700:4700::1111
    PIHOLE_DNS_4=2606:4700:4700::1001

Looks like the Pi-hole is functioning though:

*** [ DIAGNOSING ]: Pi-hole log
-rw-r--r-- 1 pihole pihole 59256563 Apr 18 09:10 /var/log/pihole.log
   -----head of pihole.log------
   Apr 18 00:00:12 dnsmasq[23001]: query[A] self.events.data.microsoft.com from 192.168.0.11
   Apr 18 00:00:12 dnsmasq[23001]: gravity blocked self.events.data.microsoft.com is 0.0.0.0
   Apr 18 00:00:17 dnsmasq[23001]: query[A] self.events.data.microsoft.com from 192.168.0.11
   Apr 18 00:00:17 dnsmasq[23001]: gravity blocked self.events.data.microsoft.com is 0.0.0.0
   Apr 18 00:00:18 dnsmasq[23001]: query[A] tracker.empornium.sx from 192.168.0.199
   Apr 18 00:00:18 dnsmasq[23001]: forwarded tracker.empornium.sx to 1.1.1.1
   Apr 18 00:00:18 dnsmasq[23001]: query[AAAA] tracker.empornium.sx from 192.168.0.199
   Apr 18 00:00:18 dnsmasq[23001]: forwarded tracker.empornium.sx to 1.1.1.1
   Apr 18 00:00:18 dnsmasq[23001]: validation result is INSECURE
   Apr 18 00:00:18 dnsmasq[23001]: reply tracker.empornium.sx is NODATA-IPv6
   Apr 18 00:00:18 dnsmasq[23001]: validation result is INSECURE
   Apr 18 00:00:18 dnsmasq[23001]: reply tracker.empornium.sx is 91.132.60.27
   Apr 18 00:00:23 dnsmasq[23001]: query[A] self.events.data.microsoft.com from 192.168.0.11
   Apr 18 00:00:23 dnsmasq[23001]: gravity blocked self.events.data.microsoft.com is 0.0.0.0
   Apr 18 00:00:29 dnsmasq[23001]: query[A] self.events.data.microsoft.com from 192.168.0.11
   Apr 18 00:00:29 dnsmasq[23001]: gravity blocked self.events.data.microsoft.com is 0.0.0.0
   Apr 18 00:00:29 dnsmasq[23001]: query[A] wpad.ackis.duckdns.org from 192.168.0.11
   Apr 18 00:00:29 dnsmasq[23001]: config wpad.ackis.duckdns.org is 192.168.0.199
   Apr 18 00:00:29 dnsmasq[23001]: query[A] asf.ackis.duckdns.org from 192.168.0.11
   Apr 18 00:00:29 dnsmasq[23001]: config asf.ackis.duckdns.org is 192.168.0.199

[Ackis]

I had IP6 turned off on my windows machines, but I enabled it and this is the info now:

Ethernet adapter Intel:

   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::a078:4794:81d5:e06d%12
   IPv4 Address. . . . . . . . . . . : 192.168.0.10
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.0.1

On the Pi Hole server:

ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.200  netmask 255.255.255.0  broadcast 192.168.0.255
        inet6 fe80::f4ea:4d4b:d3d4:8d39  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:09:6f:0c  txqueuelen 1000  (Ethernet)
        RX packets 240908  bytes 71776390 (68.4 MiB)
        RX errors 0  dropped 356  overruns 0  frame 0
        TX packets 146128  bytes 44089984 (42.0 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

I looked at the thread Use IPv6 ULA addresses for Pi-hole and because my IP6 address doesn't start with a FC or FD that script doesn't work. Is fixing it as simple as putting my IP6 (fe80::f4ea:4d4b:d3d4:8d39) address into the setupvars file?

Edit: I did what I suggested (added my IP6 to setup vars). Here's a new diagnoses log: https://tricorder.pi-hole.net/7e3onqldki