Once one client used an Exellio DP-15 cash register with a TP-Link router, but when he replaced the router with MikroTik, the Exellio cash register stopped working.
For diagnostics, I immediately decided to see if the cash register was trying to establish any connections, for this I opened the IP – Firewall menu on MikroTik and selected the “Connections” tab, there I saw that many connections were being created to DNS 192.168.88.1:53, and other connections from he is not.
The IP address and DNS were entered manually in the network settings of the cash register, if you switch to DHCP, then the problem was similar.
I advised the employee to specify some public DNS first, for example 184.108.40.206, when he did this, I saw in the “Connections” tab only one connection to this DNS and another connection appeared with the server that Exellio was working with.
That is, the problem was solved by specifying the public DNS first. With DHCP, they can be specified in the IP – DNS menu. The cash register did not use the secondary DNS, and the domain of the server to which the cash register was connected did not resolve with the local DNS from MikroTik.