The Unraid server IPv6 broke. I couldn't ping mothership.unraid.net from the server when it was using IPv6. But I could ping mothership.unraid.net's IPv6 IP from other workstations on my network.
root@UNRAID:~# ping mothership.unraid.net
PING mothership.unraid.net(2606:4700:20::681a:275 (2606:4700:20::681a:275)) 56 data bytes
From 2604:2d80:500a:6200::949 icmp_seq=1 Destination unreachable: Address unreachable
From 2604:2d80:500a:6200::949 icmp_seq=2 Destination unreachable: Address unreachable
Flushed the IPv6 on the interface and restarted the API
root@UNRAID:~# ip -6 addr flush dev br0
root@UNRAID:~# unraid-api restart
Via v4 I can get to mothership.unraid.net. And it is showing connected and online on connect.unraid.net
root@UNRAID:~# ping mothership.unraid.net
PING mothership.unraid.net (172.67.69.176) 56(84) bytes of data.
64 bytes from 172.67.69.176 (172.67.69.176): icmp_seq=1 ttl=54 time=17.6 ms
64 bytes from 172.67.69.176 (172.67.69.176): icmp_seq=2 ttl=54 time=15.1 ms
64 bytes from 172.67.69.176 (172.67.69.176): icmp_seq=3 ttl=54 time=14.6 ms
64 bytes from 172.67.69.176 (172.67.69.176): icmp_seq=4 ttl=54 time=15.9 ms
--- mothership.unraid.net ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 15069ms
rtt min/avg/max/mdev = 14.644/15.812/17.627/1.133 ms
<-----UNRAID-API-REPORT----->
SERVER_NAME: UNRAID
ENVIRONMENT: production
UNRAID_VERSION: 6.11.5
UNRAID_API_VERSION: 3.0.1
UNRAID_API_STATUS: running
API_KEY: valid
MY_SERVERS: authenticated
MY_SERVERS_USERNAME: hawkcfa
CLOUD:
STATUS: [ok]
IP: [104.26.2.117]
MINI-GRAPH:
STATUS: [CONNECTED]
SERVERS:
ONLINE: UNRAID[owner="hawkcfa"]
OFFLINE:
ALLOWED_ORIGINS: http://localhost, https://localhost, http://unraid.local, http://IPV4ADDRESS, http://unraid, https://connect.myunraid.net, https://staging.connect.myunraid.net, https://dev-my.myunraid.net:4000
</----UNRAID-API-REPORT----->
I still can't ping outside my internal network via IPv6 from Unraid. So it is only band-aided to connect via v4. It still can't/won't connect via v6 because the Unraid server itself IPv6 is broken. I have VMs on the Unraid that get IPv6 from my DHCPv6 server and they are working just fine. So the problem is definitely with IPv6 on Unraid itself. It really is acting like the Unraid server has lost or unable to implement the default route for v6.