pulsar1911:

I tested it again with latest snapshot for xiaomi-mir3g MT7621 29.03.2020.
It is still the same for me. 2.4GHz works fine, if i just change to 5GHz with the same settings the upload is broken (~1MBit).
I tried all the WiFi settings available, but still no luck getting it to work.

(Xiaomi 3G Post)

pulsar1911:

Update from my side: Today I flashed a new snapshot (19.04.2020) and the ethernet ports broke probably because i kept saving settings. So I flashed again over wifi and started testing from scratch again.
In the 5GHz client wifi setting i typed a random number (3000) in the setting "Fragmentation threshold". And now it seems to work perfectly.
Can someone test that too?

bill888:

I just tried this on RT-AC57U with 19.07.2. Any attempt to edit the fragmentation threshold in LuCI seems to break routing. I could ping my ISP facing router LAN IP on other side of the bridge, but could not ping any external internet IP address.

I then installed latest r13021 snapshot and discovered the interface names have changed. eg. WAN interface should be eth0.2. It is currently called 'wan'. The switch menu is missing from LuCI and the /etc/config/network file is missing factory default switch/VLAN configuration.

I decided not to carry out any further tests until the issue with switch configuration is restored to normal with future snapshots.

caiom:

I can confirm this bug with C50 v4 (BR). The upload speed on the 5Ghz radio is, at most, 1mbps.

However setting the Fragmentation Threshold to 3000 solved the issue aswell!
Now it is 70mbps :)

TBeckler:

I can confirm this bug on a Netgear R6220 (MT7621). Same observations like above.

• Only present using relayd (standard access point operation in 2.4 GHz and 5 GHz WIFI shows high throughput) with any WIFI client
• Only present using 5 GHz WIFI (using relayd on 2.4 GHz WIFI is OK)
• low throughput ~1 Mbit/s
• issue can be "compensated" by changeing the "fragmentation threshold".

Thank you for this bug report, as

• I always thought it is related to my specific router and the hardware (FS#3080 - ramips/mt7621 Netgear R6220 WIFI 5 GHz issue).
• I never thought this could be related to relayd

Can somebody explain, why this issue is related to "relayd"? I though "relayd" is not affecting the "WIFI low level performance", as it is operating one or two layers higher

VA1DER:

I believe this has less to do with relayd and more to do with the wireless connection. Specifically, my MT7621 device has a very hard time sending data upstream to my primary Broadcom router.

I have had DD-WRT, and OpenWrt on this device back and forth several times in the last few days and it doesn't matter what firmware I have on it, the upstream transmit is horrible. At times I can watch the association flip between modes every few seconds, almost always with a strong downstream and a very weak upstream. Even at times when the association looks stable, though, upstream traffic is terrible.

I suspect that most people are using relayd because WDS doesn't work, and the most common time when WDS doesn't work is when you are trying to use it between, say, Broadcom and Mediatek devices. That is why people are experiencing this bug and associating it with relayd.