Hi!
Is the RT-AC51U reliable and is the 5GHz wifi working now?
I'm thinking of using it but I see some older posts talking about fairly frequent reboots.
Thankful for some current info,
Have access for few of them, so tested it.
With OpenWRT 5GHz doesn't work (it starts but maximum I'm able to get through is 20Mbps vs with Asus stock FW it goes as fast as possible).
There is a fix for 5GHz and should it be already in available image, but..
Not sure if it works properly, because when I try apply the fix via ssh and it show me different md5 still even I'm using the 23.05.4 (r24012-d8dd03c46f) and if the fix is 'in' I'm assume that it should be 1:1.
With this image in the wireless the info about available power ended up always max 3mW - with the patch applied is seems to me it actually helped a bit and higher mW can be seen.
But that does not helped much at all.
As conclusion, it does work fairly well as dumb AP/2.4 only:
a) wired connection > LAN ports + 2.4GHz AP
b) where the backhaul done on 2.4GHz WiFi (the WDS) > therefore the LAN ports remain usable for wired(!) connection.
c) if it's WDS (backhaul) + AP (here the 5GHz could be really usable..) that does not perform well (obviously: cutting speed to half at least + adding delay, jitter, bufferbloating a lot) - definitely not usable.
Conclusion - forget about 5GHz with OpenWRT.
Because chipset line of mtk76x0 (this device having 7610E for 5GHz) is fairly old, none will fix that as it being deprecated by vendor as well.
So if 5GHz needed - do not flash this device, stock works well (even with 1x1).
Note also that stock FW does support WDS but:
function only support [Open System/NONE, Open System/WEP] security authentication method.
Here is the FAQ Asus article
So that can be even impossible to set up not to mention it's not secure anymore for more than a decade.
Therefore if WDS(wireless backhaul/no ethernet cable possible) is only option, it can be done only by OpenWRT.
This can be the reason why if I did OWrt set up WDS/WPA2 - it worked only reasonable on 2.4 and the 5 network topping up with 2-3Mbps as WDS or 10 as AP behind WDS or barely 20 as wired.
(And AC51U doesn't support WEP - so it's only open network for WDS - what a crappy device.)
Also it requires the Legacy to be chosen for AP - possibly pushing the WiFi performance rather down.
This can be probably the reason(?) why the 5GHz 7610E chipset (or almost all of them in general) does perform so badly under OpenWRT - for it to work vendor probably heavily modified driver as there are constraints because of overall weak chipset.
And as none knows how to reproduce this set up in OWrt drivers so it exist in some default not fitting all scenario.
Also there is Tx power adjustment for TPC (Transmit power control) in advanced settings in stock FW - I do believe that is also the part missing in OWrt driver - it does have 5 steps.
All this 76x0 having problems with TX will be because of different vendors managed to adjust driver really differently to fit as much possibilities being constrained by it's design(?).
That can't be easily transported into OWrt drivers unless one goes and do it device by device from some proprietary undocumented blob.