raspberry pi - no ethernet connection on unrelated IPv6 change in router [closed]

My raspberry pi is reachable via Putty at 192.168.0.112. As soon as I change IPv6 settings in the router from DHCP-PD enabled to disabled (because I am trying to understand of IPv6 works), I can no longer connect to the pi. The pi is even not showing up when I scan the full subnet 192.168.0.0/24. The router has DHCP (IPv4) enabled, but the pi has a manually assigned static ip.

How might this be related?

Here is the output of ip addr show eth0 of my pi:

eth0: flags=4675<UP,BROADCAST,RUNNING,ALLMULTI,MULTICAST>  mtu 1500
        inet 192.168.0.110  netmask 255.255.255.0  broadcast 192.168.0.255
        inet6 XXXX:XXXX:XXXX:XXXX::11f8  prefixlen 128  scopeid 0x0<global>
        inet6 fe80::ba27:ebff:febb:cccd  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:bb:cc:cd  txqueuelen 1000  (Ethernet)
        RX packets 2669  bytes 306878 (299.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 528  bytes 123539 (120.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Solution 1:

Not related. Static IP addresses on a host are unaffected by DHCP settings on the router's WAN interfaces.

Further, DHCPv6 is different from DHCPv4. They are separate protocols.

Try using IPv6 only to connect to the host. You already have an address. Consider adding a known address via such mechanisms as EUI-64 or static host identifier aka ip token on Linux.

Should v4 be required, do packet capture on both source and destination hosts, and analyze to see what is happening.