Firmware 1.2.0 Build 20231229 Rel 43148 broke my network
So, I have fiber with a static IP. This plugs into the main Deco x55 router (the other 3 are backhaul satellites). All 4 Deco units are the same models. This router is the DHCP server for my 192.168.6.1 network. I use a Pihole server for DNS only (DHCP server is disabled) on 192.168.6.6. The main Deco point to only the Pihole server for DNS... I have no secondary DNS assigned. Up until yesterday everything was working fine. And by everything, I mean that I run an always online network because I host game servers, voip servers, and web servers. However, when I applied the "new firmware" on all the Deco points as directed by the TP Link app, it broke ALL inbound traffic. Outbound still works and internal LAN connections still work. But ALL of the servers are now unreachable from external.
I noticed 3 of the 4 Deco points received the 1.2.0 Build 20231229 Rel 43148 version of firmware while 1 of them received 1.5.1 Build 20240417 Rel 52783.
Also... there is an issue with the Subnet mask settings now. The main Deco point (Router) seems to have changed it's subnet mask to 255.255.252.0 after the firmware update instead of what the rest of the network has been using for years 255.255.255.0. I checked all the servers including the DNS PiHole server and they are all still set to 255.255.255.0. However, when I try to change the Deco point (Router) subnet back to 255.255.255.0 from within the TP-Link app ... it states
"LAN IP address and DNS server address (192.168.6.6) cannot be in the same subnet. Please enter another."
What's the deal?! They have been on the same subnet for years without issue. Even the network guys at work said that error is wrong and you can absolutely have the DNS server and LAN IP address on the same subnet. They all point fingers to this being a firmware bug that got introduced since everything was working fine prior to the update.
So... at this point I think I need to revert to the previous firmware on all the devices otherwise my servers will remain unreachable. How do I go about reverting the firmware? On the mobile app... there does not appear to be any way to revert firmware. The only options are: System Time, Update Deco, Reboot Deco, and Reboot Schedule.