Just want to share some really weird result(see pic below)
You would think that using stock OEM firmware for the bandwidth test will be always
better than OpenWRT. However, it is the opposite.
On OpenWRT firmware =340Mbits/s VS Totolink Stock OEM Firmware=272Mbits/s at 5GHz band
Wireless client(iperf3 client) is using an Intel AX200 PCI-E card on my gigabyte motherboard.
pfSense firewall router is running iperf3 server.
Maybe my testing is distorted in some way. 
Not sure what to comment on this report.
These are ppl who have issues with the 5GHz radio not working when installed OpenWRT firmware.
I add in a line under wifi device, option country 'xx'
xx- denotes my country code.
save the configuration wireless file.
run the command: uci commit wireless
reboot the router
The result is all my radios, both 2.4GHz & 5GHz show: Device is not active.
All radios are disabled.
I reverted back to the old settings, remove: option country 'xx'
Then everything back to normal. What I have done wrong?
What does the Country Code look like in LuCI > Network > Wireless ?
Any special reason you're using UCI rather than LuCI to do configs?
Because using LUCI to do the setting is broken for 5GHz radio,
according to @nagato1118 : X5000R wireless 5GHz issue - #18 by nagato1118
Yeap,it sure does not work, I tried it just now
SSH in to the router and run (again) -
cat /etc/config/wireless
Post as preformatted text.
Here
-----------------------------------------------------
OpenWrt 21.02.2, r16495-bf0c965af0
-----------------------------------------------------
root@OpenWrt:~# cat /etc/config/wireless
config wifi-device 'radio0'
option type 'mac80211'
option path '1e140000.pcie/pci0000:00/0000:00:01.0/0000:02:00.0'
option channel '1'
option band '2g'
option cell_density '0'
option htmode 'HE20'
config wifi-iface 'default_radio0'
option device 'radio0'
option network 'lan'
option mode 'ap'
option encryption 'psk2'
option key
option ssid 'OpenWrtX5000R_2.4GHz'
config wifi-device 'radio1'
option type 'mac80211'
option path '1e140000.pcie/pci0000:00/0000:00:01.0/0000:02:00.0+1'
option channel '36'
option band '5g'
option htmode 'HE80'
option cell_density '0'
config wifi-iface 'default_radio1'
option device 'radio1'
option network 'lan'
option mode 'ap'
option ssid 'OpenWrtX5000R_5GHz'
option encryption 'psk2'
option key
No Country Code showing for either 2.4 GHz, or 5 GHz.
This should go in each config wifi-device section -
option country 'US' (using my country code here)
Add the option, commit it, and re-post your WiFi configs again.
I am outside at the moment.
I will try it again when I get home.
Yes, correct I did insert the setting at config wifi-device section,
and I keyed in my own country code. Not 'US'
The result is Device is not active, as I mentioned earlier.
Wouldn't it make a difference, if I key 'US' for the country that I pretend to be coming from?
Well, I will not be compliant with the regulatory domain 
You need to use your own country code.
For some reason, your changes are not showing up in the wireless config file.
Instead of using UCI from the SSH command line, I would suggest downloading the nano text editor package.
opkg update
opkg install nano
Note: If you're a Windows user, WinSCP is an excellent tool...
Backup your configs first.
Then, just edit the config file, make your changes, and save it.
No need to do a uci commit when using a text editor.
Finally, you need to restart wireless...which is the step I think your missing
Run wifi up to bring up all wireless radios.
I backed up the tar.gz file, and unziped it to modify the etc/config/wireless file.
I add the ``option country 'US'` just for the sake of testing only.
Later I will change to my own country code.
Save the wireless file, after editing using notepad++.
Created the tar file with 7-zip and then compressed again in gz format
Uploaded the modified gz file using Restore
Once was restorsed, the router will automatically rebooted itself
Once the router rebooted, I restarted the interfaces.
I ssh into the router, and do a: cat /etc/config/wireless
The result was the same, the line that I keyed in option country 'US'
in the config wifi-device section, it did not stick.
What I typed was simply not showing up.
The edit with Notepad++ could be exaclty what needs to be avoided.
So make sure your editing correctly by clicking 'Unix'
^this.
You avoid the unix/windows translations issue. unix uses LineFeed only for new lines. Windows uses Carridge Return/Line Feed for new line. that WILL make unix barf.
WinSCP gives you dual explorer type windows and you can copy/paste into the internal editor and it will save it to your router with the correct unicode.
Before I went into this path.........
I did tried another path, that is install nano in my router
SSh into my router and open up the wireless text file:
nano etc/config/wireless
Open the file with nano, and add the line:
option country 'US' into config wifi-device section for both Radio0 and Radio1.
I saved the file, exit then I do:
uci commit wireless
reboot
The router rebooted, I SSH again and did a: cat /etc/config/wireless
But in the end, the result is the same, I cannot get
option country 'US' to stick. This line is completely disappeared.
So shoud I try WinSCP?
As mentioned above, when you use a text editor, you don't need to run uci commit.
Also mentioned above, run wifi up after editing and saving the config file...a reboot is not needed.
And finally (you guessed it...mentioned above), you need to use your own country code.
Give it a try...I use it almost exclusively.
It's also has a editor (will default to Notepad, or whatever your default text editor is), so the same principles apply for editing in WinSCP as in nano. (make the change, save it, no uci commit, run wifi up, use your own country code).
Ok now the line: option country 'XX' (example only XX is not a real country code) is sticking
But...........I have some problems:
In Luci, Network, Wireless, click on edit, go to Advanced Setting tab, Country = BLANK/Empty
2.4Ghz radio is completely down, and it is not active, no matter how times I restart. 5GHz radio is working.
RPCerror message in red appeared. Once you press the dismiss button, the Luci web page will
not load at all. Only can see the spinning wheel, with the message: loading view....I rebooted
the router, and now wireless GUI is missing, so now to fix this problem?
I ssh into router, and type the command: nano etc/config/wireless,
nano cannot find the wireless file.
I went ahead and grabbed the sysupgrade firmware and reinstalled OpenWRT again.
Only then, I am back in business.
I think is best to leave out the option country 'XX', so that it will run more stably.
I ran the steps I posted for 2 or 3 Country Codes, and it worked every time.
I think I would do a reset, and re-configure from scratch.
Hi, would you mind telling me which router you are testing? X5000R?
The principles for editing config files in OpenWrt work the same.
It's not device dependent.
If you're having this much difficulty with manual configuration, try rolling back to 21.02.1 or 21.02.0, and see if LuCI configuration works.
I would still re-configure from scratch with 21.02.1 or 21.02.0.
If you want to try the snapshot -
Note that it does not include LuCI, so you will have to install it.
opkg update
opkg install luci
Good luck.
Thank you for your patience & guidance. 
I manage to get it working now.
When I encountered the Luci was crashing, I would just do *perform reset* as shown in your previous post.
I edited using Nano on the /etc/config/wireless text file on the 5GHz and added:
option country 'XX" XX- my country code.
save the file
run the command wifi down and then wifi up
everything is working fine.
As long as I don't touch the 5GHz radio interface setting, and press Save & Apply button,
I won't crash Luci wireless interface.
I have no idea of rolling back to the previous release. Like: 21.02.1 or 21.02.0
This link above that you have shared, which release it this?
Thank again for your help. 
