4011 is a strong toy - i suppose will deal with pppoe at 2gbps without problems; pairing it with a 4x sfp+ switch, some direct attach cables [4011 is working with, probably not stable, but the connection is negotiated at 10gbps] or s+rj10 modules, throw there a 10gbps capable nas, some cheap 10gbe pcie adapters… and you’ll have a good 10gbe soho network for a really small price!
but i also want 160mhz working. and some other things [maybe i’ll obtain solutions from forum]
I too have this problem. first 24 hours or so everything was fine and I have not been able to see the 802.11AC radio since. I have upgraded software and firmware, restarted, I am nearing factory reset but its at a remote site.
the wlan2 is working perfectly. wlan1 is enabled but not running and cant be seen.
I see lots of posts about it and no real solution.
Same here .. wlan1 is there but clients can’t see SSID .. seems to be a common problem. Anyone contacted Mikrotik Support?
yes. no reply. only 80mhz option working so far.
I’ve contacted MT Support also .. lets see what they say. I checked the supout.rif viewer and it shows “status: initializing” for wlan1 .. i guess it’s maybe a driver problem (crashing or something like that)
Same issue here. Was loving the 5ghz throughout now just initializing.
To confirm at the moment a reboot fixes mine.
I’m having the same issue. Sometimes the 5GHZ network disappears after just a few hours, sometimes a few days. I tried upgrading to the beta firmware (because it mentioned stability issues with ARM wifi devices) but that didn’t change anything.
One interesting thing .. i have another RB4011 and it’s wlan1 is working all the time. I have at least one client connected all the time so it’s never idle, i am not sure but i think it has something to do with it … maybe some with problems could try to connect at least one device permanently (just to test)
same problem here.. wlan1 5ghz disappear. any fix for this issues?
more tests [requiring a lot of minutes to spend]
- country: romania, frequency mode:regulatory domain, frequency: auto, channel width:xxxxxxxx - will select one of available channels [5500 or so], will search for radar for ~10 minutes, only single 80mhz made available
- changed country to usa, auto on everything else - the same result
- changed country to ‘debug’, selected a channel from lower region - the same result
- channel width xxxx, secondary channel: auto (80+80mhz non-contiguous) - status will show selected channels, but adapter (intel 9560) will connect on main channel at 144mbps (i’m not so sure that adapter will support 80+80); but AcrylicWiFi will see something like a wide band.
searching for radar will not display entries in logs, with “wireless” logging rule manually added.
5ghz band being disabled from time to time seems to be caused by “radar” interference; there was documented some cases when an iphone (6?) caused such interference - can’t find that article right now; also weather radar.
Still not fixed in 6.44 
Still not fixed in 6.44
Same here, AP says running, but there is no current tx power and no becons being transmitted.
Disabling and re-enabling, status will stay as initialising
From https://forum.mikrotik.com/viewtopic.php?f=3&t=138613&p=712855&hilit=4011#p712855
Try not using auto frequency and set the frequency manually.
Ok, after many tests i have a “solution” .. you just need at least one 5Ghz Client connected all the time and the wlan1 will always work. The problem is just happening when there is NO client connected for a specified time, then it will “crash”
I already told this to MT support and hope they fix it soon.
Yep, I’d agree with that forcing the frequency doesn’t help.
Next day same thing dead AP, nothing was left connected.
I have the same problem too I also sent supout.rif and no response so far (Ticket#2019031222002841).
Edit
Just to not be “me too”-only post: for me that problem happens even in super channel with locked frequency, so the DFS and automatic frequency selection can be ruled-out.
i’d like to see someone test it in a Faraday cage, to avoid any radar interference.. i bet that will get the very same results.
+1
someone did it with ubnt: https://www.eduitguy.com/2018/06/14/ubnt-infrastructure-part-8-dfs-nightmare/
I tried tweaking various settings and the WiFi dies as before. Support advised net install, but currently I don’t have a spare in the 100mi radius 
So far I attached a “diagnostic device” on site consisting of an hAP ac (a huge overkill but I had one half-fried on the shelf :p) which connects to the 5ghz and pings th rb4011. It’s stupid but it works - the radio just cannot have 0 devices connected (and the problematic unit is in a residential location).
I wonder if MT found a reason for this weird behavior?