A few months ago, we found a problem with one the Mikrotik Routerboard RB1100AH unit. We discovered that the fans are not working. As we have a cold spare unit, I just transferred the latest backup to the new unit.
After the reboot, everything began to work. That was easy on the first sight. However, I discovered soon that the remote offices are not connected to the central location. The VPN links were down.