It all began with the new server installation, everything worked fine till I demote the old server and changed the IP ADDRESS schema from 192.168.1.0/24 to 192.100.100.0/24. Since than I am only having AAA records in my DNS with IPV6. Tried the following but nothing worked.
1. Microsoft FIXIT to disable ipv6 in each and every pc including server.
2. manually editing registry with DISABLECOMPONENT DWORD fix.
3. unchecking IPV6 in each and every computers networking properties.
4. deleting all IPV6 entries in DNS.
5. did netdiag /fix command and restarted the server.
Thankfully the domain users are able to contact server with hostname and ipv4 but If no client pcs are able to ping each other or from the server. In fact, if ping from the same PC it pings through ipv6. Surprisingly, I can ping through ipv4 only for a while when a PC is in shutting down mode or restarted but once its on desktop it stops pinging again and shows “request timed out”