How to organize a backup communication channel using a Wi-Fi bridge?

Question

network hardware

Good day.

Our company decided to organize a backup Internet channel in case the main one fails. It is implemented in the following way:

A Wi-Fi bridge is configured using two Mikrotik SXT 2 devices. One is connected to the Internet from the apartment, and the second to the office. The problem is that pings to the remote SXT do not go. and accordingly it is impossible to select it as a gateway.

I broke my whole head, tell me where to dig.