I've now had two out of six Mikrotik Metal 5GHz fail.
All my units are kept indoor climate controlled (20-24C) area connected to antennas through Waveguide. One day my system reports in failover. Trace problem to a link consisting of two metals. After troubleshooting I replace one of the metals and restore settings which resolves the problem.
I brought problem metal home and put it on bench. Reset everything to default with radio disabled. Looks OK. Walk away for a while and come back to find it at 50C on /System Health.
First unit had been in production for maybe 6 weeks working fine. The second unit in production the longest, maybe 6 months.
I have seen a couple random threads reporting similar problems with the 2GHz version as well. Problem exhibits as the radio part stops working but unit itself is otherwise OK. Scan doesn't report anything and if put in AP mode the unit generates no signal. The obvious tell for this problem is the unit's internal temperature. Under normal conditions (indoors) my units register between 37C and 42C. When they start having problems the internal temperature goes up to 50C.
FYI.