What FW, Openwrt or Xiaomi?
If FW is Openwrt, then it has no reason for SSH not to work if it was working before (even without Luci). Unless, you opted to not save configuration while doing FW upgrade, and Openwrt default access IP has been reverted back to 192.168.1.1.
Is it possible to make a mod to have a USB port?
Are you asking how difficult it would be to modify the SoC to add a USB port???
not necessarily work directly with the soc, but if there are random points on the pcb that are already connected to the soc, we can solder wiring to make use of usb 2.0 for example.
because the soc from what mediatek discloses even supports usb, but you would have to have the tracks somewhere on the ax6000's pcb to make a mod of this type.
Including, but I really doubt it's possible to do this, is to activate the 2.5Gb speed that the soc also supports on the ethernet port, but I would have to see what Redmi did to disable this speed.
The switch chip used probably does not support this speed.
As an example of USB mod support, there is the Archer C6 V2, but the mod on it is quite risky because it involves direct soldering to the soc.
on the ax6000 it would be impossible to work directly with the soc, because the MediaTek MT7986A uses bga soldering.
The hope would be for Redmi to have connected the dots and randomly left the lines on the PCB.
Could you share the url of this Chinese forum? thanks
Interesting link! So memory can be expanded to 2GB if you are very brave and skilled in soldering.
Very simple question for those more knowledge than I, can this router support communicating over WDS or 802.11s on one 5Ghz channel at 80Mhz width, and having an access point on another 5Ghz channel at 80Mhz width?
In case someone still buys this one, latest firmware I got ( 1.0.68 ) does not allow the downgrade. Works ok with TFTP downgrade method.
Don't see any reason why it would be possible 
A single radio can only be configured to use a single channel, hence the 802.11s mesh will use the same channel as the AP (if you would like your 5ghz radio to serve both as mesh backbone and access point)
Hello guys:
Is there any way to let LEDs like in the previous snapshot versions? In the latest version, both LEDs are off. I could set up part of the previous version but now when the router is starting the first four LEDs don't blink like before, then I don't know if the router is starting until the system is completely loaded.
This is my current config:
config led 'led_wan'
option name 'wan'
option sysfs 'led_1'
option trigger 'netdev'
option dev 'wan'
list mode 'link'
list mode 'tx'
list mode 'rx'
Could you please help me with this?
Than you so much. 
BUG fixed.
Can you please give us the method for the tftp downgrade?
in the wiki there is this section: " TFTP instructions for the stock layout "
Did you mean that?
Isn't it usually applied after softbrick?
Thank you so much.
Works properly again.
Hello, my first time commenting here. I have OpenWrt (ubootmod layout) installed on my Redmi AX6000. Yesterday I tried to access Luci and came across this error.
I haven't touched packages lately, I don't know what could have caused this problem. But I found a forum saying that the command "opkg install luci luci-compat" would solve the problem, and yes I was able to log into Luci again. I updated sysupgrade to the latest version, which could be a bug in the version. And my router has since died, I can't even ssh or telnet. Don't have default gateway. It's probably bricked. I don't know what to do now, I don't know if anyone can help me.
You will need to connect a serial cable if you cannot access via ssh or web. See the wiki page.
I just build the latest commit and found terrible 5 GHz performance after a few hours of uptime. Speedtest app on my phone gave initial ping values >900 ms and very slow to no loading of websites. I did not see anything in dmesg nor logread output. Reverting to an image I built on 24-Feb restored the fast/reliable traffic. No idea what commit/commits could be to blame.
There is a chance for https://openwrt.org/docs/guide-user/troubleshooting/failsafe_and_factory_reset to work, so try that first.
Hello:
Since I've installed OpenWrt SNAPSHOT r25442-97f542238a, I have problems with my wifi 2G.
Everything works fine but suddenly wifi 2G stops working and I need to reboot the router. Don't work only restarting the wifi. All logs look fine.
My 2G devices can connect but starting a loop disconnecting and connecting until restarting the router.
The Wifi 5G is working fine for the moment.
I don't know if it can be the same problem.
Greetings.