MT7915E slow speed in STA mode

I have two redmi ax6s routers - one in AP mode and the other configured in STA mode.
Both running on OpenWrt SNAPSHOT r20032-639419ec4f

I'm able to transfer from my notebook with an intel wifi card via the router in AP mode to a machine connected to its ethernet switch with a constant speed of over 100MB/s (notebook -> AP -> Machine connected to ethernetswitch on the Router).

When I do the same from a machine connected to the switch of the router IN STA mode I can reach only <7MB/s (Machine connected to switch in STA Mode -> Router in STA mode -> Router in AP mode -> Machine connected to router's switch).

Speed is in both directions about the same in both scenarios.

The config of the router in STA mode:

config wifi-device 'radio1'
        option type 'mac80211'
        option path '1a143000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0'
        option band '5g'
        option country 'CH'
        option cell_density '0'
        option channel 'auto'
        option htmode 'HE160'

config wifi-iface 'default_radio1'
        option device 'radio1'
        option mode 'sta'
        option ssid 'some ssid'
        option key 'some key'
        option network 'wan'
        option encryption 'sae'

What I've already tried:

• Using WPA2
• HT20 / HT40 / HT80
• N / AC
• different values for cell_density and distances
• physically moving the router in STA mode nearer (same distance as my notebook) to the router in AP mode.
• whatnot

Router in STA mode infos:
iwinfo wlan1 info
wlan1 ESSID: "some ssid"
Access Point:
Mode: Client Channel: 36 (5.180 GHz)
Center Channel 1: 50 2: unknown
Tx-Power: 20 dBm Link Quality: 58/70
Signal: -52 dBm Noise: unknown
Bit Rate: 136.1 MBit/s
Encryption: unknown
Type: nl80211 HW Mode(s): 802.11nacax
Hardware: 14C3:7915 14C3:7915 [MediaTek MT7915E]
TX power offset: none
Frequency offset: none
Supports VAPs: yes PHY name: phy1

iw wlan1 info
Interface wlan1
ifindex 10
wdev 0x100000002
addr
ssid
type managed
wiphy 1
channel 36 (5180 MHz), width: 160 MHz, center1: 5250 MHz
txpower 20.00 dBm
multicast TXQ:
qsz-byt qsz-pkt flows drops marks overlmt hashcol tx-bytes tx-packets
0 0 0 0 0 0 0 0 0

Luci reports:
144.1 Mbit/s, 160 MHz, HE-MCS 1, HE-NSS 1
1361.2 Mbit/s, 160 MHz, HE-MCS 7, HE-NSS 2, HE-GI 1
^^^
I've just noticed the 1361.2 Mbit/s in comparison with iwinfo's 136.1 MBit/s ?! Is that correct? Or are the 144.1 Mbit/s related to the 136.1 MBit/s of iwinfo?

and for my notebook luci says:
1921.5 Mbit/s, 160 MHz, HE-MCS 9, HE-NSS 2
1814.8 Mbit/s, 160 MHz, HE-MCS 9, HE-NSS 2, HE-GI 1

While playing around with different settings I found a second issue:
Initially I had set the router which is in AP mode to channel = auto. Sometimes after rebooting the router selected a dfs channel and then I could no longer connect to it with the router in STA mode although every other wifi client is still able to do so. Solution for now is to fix the channel to a non dfs one.

Last but not least the 3rd issue I've seeing is that when try to transfer gigabytes of data through an ssh tunnel via the second setup described above I get "message authentication code incorrect" from the ssh peer most of the time during transfer. This means some bytes weren't transferred correctly. This seems not to happen in setup 1.

Please advice if you need more information.

Thx, Marc

No source file or test is named. Start by reproducing the STA-mode throughput, DFS reconnection, and SSH integrity symptoms with the supplied wireless configuration, then compare the iwinfo and iw link-rate reports; done means identifying and fixing the relevant MT7915E driver behavior with a regression test or reproducible validation.