So i have a few Mik devices, same models etc, and use similar configs for ease as the OS was build up with specific preferences necessary and keep backup units ready in case of failure etc. The issue that i came accross, I cant seem to solve so far:

Using 6.41 OS, i changed networks on my ports from 15 to 115, 36 to 136 etc and made those changes in "POOL", "ADDRESSES" etc made sure they are all updated.
However, the minutes i did that and reset the router, DNS stopped working. I went through the whole like of DNS inputs and all are the same from the older device.

I'm able to ping and run trace w/ DNS which seems to work, however, cannot use the browser as it cannot resolve DNS.

NOTE: FIREWALL, DNS were the same from the older LAN networks.

What can it be?

made those changes in "POOL", "ADDRESSES" etc made sure they are all updated.

Can you be more specific about the "etc."?
In particular, have you changed the DNS address you offer to the DHCP clients under "/ip dhcp server network"?
If yes, what happens if you configure the 'Tik's address as DNS server manually at the client? If it starts working, the DHCP is the problem; if it doesn't, then it is probably someting in the 'Tik's firewall.

Sid,

On DHCP server network, I haven't changed anything as I left it the same as from previous config. This is the odd part. Also, all configs for the firewall stayed the same, as they operated well under the previous LAN network config. I kept the same interface names and networks, so i wouldn't have to change more than necessary just the critical changed to LAN network in Pool, Network and DHCP server. All DNS and Firewall stayed the same as the same of interfaces and pools etc stayed the same....

I tried expanding the bridge for another port, and the minute i did it, the whole bridged interfaces stopped having DNS.

Did this happen before or is it just my device because this is too weird. Something that simple to be changed creates so many issues that require so much time to investigate. How else can i test/troubleshoop the problem to see what might be wrong?

I understood from what you wrote that you have changed the ip subnets and I've supposed that you give 'Tik's own IP address as DNS to the clients.

Please paste here the output of "/export hide-sensitive" after eventually replacing each public address you don't want to disclose systematically by a distinctive x.x.x.x pattern. This will remove the need to suppose, assume and guess