So it seems that Tx chain 1 is busted (hopefuly another ROS updrade will un-bust it). I'd keep both chains active for Rx, it might help with UL. A thought: did you only upgrade ROS or routerboot as well? If you haven't, you might wanna try. I think it is already on last version... Also I tried to r...

Multiple TX/RX speed test results (5 meters away + 1 wall):
Phone:
Both on chain 0: DL-51,1 / UL-40,8 average
Both on chain 1: DL-16,2 / UL-40,4 average

Laptop:
Both on chain 0: DL-95,3, / UL-40,8 average
Both on chain 1: DL-21,5 / UL-38,4 average

This is it...

You switched off MIMO and set your RB to use one antenna for Tx and another one for Rx. Which doesn't really explain why this solves your problem unless there's some HW problem with RB (duplexer malfunctioning) or your wireless client(s) don't support MIMO (802.11 n devices should support it). In t...

I found solution by myself!
It was something with tx/rx chains.
Before:
Tx Chains: chain0 chain1
Rx Chains: chain0 chain1
After:
Tx Chains: chain0
Rx Chains: chain1

Now I get cca. 50/40mbps speed, whitch is ok for me.

Can somebody please explain what happened when I changed those parameters?

Hello there! I cannot find solution to my problem with RB2011UiAS-2HnD r2 wireless connection. So the problem is in limited download and upload speed (cca. 10 - 20mbps) . My WAN connection speed is 200mbps download and 40 upload . Wired LAN is working flawlessly. Software version: 6.44.3 CPU load: 2...