Netmetal 5,
I lost wireless port and after doing the upgarde to 6.20 /rb firmware 3.18.1 it still no wire less port

Check if for some reason you did not switch to wireless package. The wireless module of Netmetal 5 requires the use of wireless-fp package.

No wireless port at all, see photo???

I had the same problem. Reset equipment. I went back to 6.19, climbed 6.20. And now wireless appears.
Is there any problem with NETmETAL. I have a link with rb912(NETBOX5) duplicate. With 921 on the same link, does not work well, even by setting N.
IN AC, the behavior is worse.
We are waiting for a stable version for Netmetal. We had several crashes. When you change the power, the radio turns off the ether port. Is working better with 6.19 in the firmware is 3.17.

Yes, there are many bugs.

For example on my netmetal (6.19) when I start a wireless snooper device crash

They need some fixes

Installed RouterOS-mipsbe-6.21rc17.npk. AC remains broken. Lose interface. Reboot ethernet. IN N, does not crash when you change txpower or frequency. But compared the band in 6.19 or 6.20 dropped by half.

Thank you all, the problem solved by using wireless-fp pakage