@5Guru I can confirm that this problem has been going on since early 2025. I contacted support but never received a response. All tests were similar.
 

According to my tests, the problem started after introducing in firmware the Eco Mode function.
 

Even in "normal mode", upload speed is significantly reduced. With more aggressive eco modes, download is unaffected, but upload speed is further reduced. This isn't a hardware issue, but a router firmware issue when traffic is sent from Wi-Fi clients through the router to outside. In a local network, speeds reach up to 4 Gbps in both directions. There are no issues with a cable connection either.

I can confirm this for the EU versions. According to reviews, there may be no issues with the US versions.

Need a way to fully disable ECO-related limitations (true performance mode)
 

ECO Mode Impact

ECO Mode directly and linearly affects Wi-Fi TCP upload to WAN:

ECO Mode    Result (Download / Upload)
Normal    ~980 / ~500 Mbps
Power-Saving    ~980 / ~350 Mbps
Ultra Power-Saving    ~920 / ~210 Mbps

  @Asmodeus83 

Yes i am using the latest from here:
https://www.tp-link.com/en/support/download/archer-be800/v1/#Firmware

Updated via the router, the same version.

I have given up they will fix it soon.
For some reason no one cares anymore these days.

Thanks for confirming!

  @Joseph-TP 

I used to be able to run tests around ~3800 Mbps download and ~3800 Mbps upload on a Samsung S24 Ultra.

This is the only WiFi 7 (6 GHz 320 MHz) device i have.

But this 100% happened after some firmware update. (Router or phone.)

I didn't test the previous firmware, because i was busy with testing other stuff.
Then someone reported to me the speed got slower somewhere, then i tested it myself and indeed the speed is bad now.

I can show you with a speedtest.

On 10 Gbit network card:
TP-Link BE800 AP mode > KPN 4 Gbps fibre modem/router:
speedtest . net  / my-result / d / 29ec67a3-6ff1-44b0-a1b2-a98f29b84b32

TP-Link BE800 AP mode > WiFi 6 GHz 320 MHz:
speedtest . net  / my-result /a / 11347093290

The problem is the dropping in speed. This never used to happen.
I made a screen recording:

x266 . nl / dump / Screen_Recording_20260106_155535_Speedtest.mp4

Could of course be Samsung, but when i test on my fibre modem directly, i get link speed 2401 Mbps which does around ~1700 Mbps download and ~1100 Mbps upload in practice:
speedtest . net  / my-result / a / 11347109689

And this was 8 april 2024:
x266 . nl / dump / speedtest_tp-link_be800_wifi7_2024-04-08-3524mbps-3647mbps_samsung_s24_ultra.jpg

Same phone, same router (different software versions).

I bought the router BE800 EU v1 in August 2024. There were no speed issues until March 2025. The upload issues started after the first firmware update, version 1.2.x, around March 2025. All subsequent firmware versions, including the latest 1.3.3, have this issue.

My devices for testing:

Dev1. Desktop PC with 5 Gbps Realtek Network Card (driver 1126.27.50.919 from 19.09.2025)

Dev2. The same! Desktop PC with Wifi7 Intel BE200 (driver 24.10.0.4 from 11.11.2025)

Dev3. Xiaomi 15 Ultra with full support WiFi7 and 6GHz range (HyperOS 3.0.7.0)

I also have an MSI laptop with a similar Intel BE200 WiFi7 card, and the results are the same. That's why I didn't provide screenshots.

LAN-LAN
1) Dev1 (Ethernet) <-> Dev3 (6Ghz WiFi Channel Width:320)

3695/4176

2) Dev2 (Intel BE200 6Ghz) <-> Dev3 (the same 6Ghz WiFi network Channel Width:320)

1586/1481

For internet testing, I created a simple configuration. BE800->10Gbps FO SFP+->Switch Mikrotik SFP+->1Gbps->WindowsPC.
BE800 and WindowsPC are located in the same L2 segment and the same subnet.  The openspeedtestserver is up on Windows PC. Windows PC will be Dev4.

LAN-WAN

1. Dev1 (Ethernet) <-> Dev4 (Ethernet)
   983/968
2. Dev2 (Intel BE200 6Ghz) <-> Dev4 (Ethernet)
   984/664 (Eco Mode: Normal)
3. Dev3 (Xiaomi 15 Ultra) <-> Dev4 (Ethernet)
   978/572 (Eco Mode: Normal)
4. Dev2 (Intel BE200 6Ghz) <-> Dev4 (Ethernet)
   956/436 (Eco Mode: Power-Saving Mode)
5. Dev2 (Intel BE200 6Ghz) <-> Dev4 (Ethernet)
   984/301 (Eco Mode: Ultra Power-Saving Mode)
6. Dev1 speedtest.net (Eco Mode: Normal)
   888/835
   https://www.speedtest.net/my-result/d/ad48199c-71d3-481f-bb56-46fef0fa6543
7. Dev2 speedtest.net (Eco Mode: Normal)
   780/335
   https://www.speedtest.net/my-result/d/3e1a2568-285e-4f78-b696-96e1138fd7f2
8. Dev3 speedtest.net (Eco Mode: Normal)
   891/285
   https://www.speedtest.net/result/a/11348077784

  @Joseph-TP 

Thanks for the reply.

But i am not going to help with something so obvious.

Some extra info:
When i connect to a 2.5 Gbps port the WiFi 7 - 6 GHz speeds are much faster than when connected to a 10 Gbps port on the same modem.

I only see flow controller options on LAN. In AP mode. So could be a modem side issue, which i highly doubt. 

I don't have time nor am willing to share more information.

If it can't be reproduced, too bad then for me. The device just will no longer be used in comparisons.

Best way would be if we could load older firmware versions, but we can't so yeah, good luck.

  @Joseph-TP 

1. Where can I send the backup file? It may contain confidential data, so I don't want to make it publicly accessible.

2. Okay, I'll run a few more tests in the next few days on 5G, using different channels, channel widths, and receiver power levels. Although that's a rather odd request, since the problem also occurs with 5G and 6G, where there are no other devices, other than my router.

3. I've already tested various Flow Control parameters on both the LAN and WAN side, and on the Mikrotik device. All changes had no effect on the results.

4. I also tested QoS and it also does not affect the results in any way.

  @5Guru 

"When i connect to a 2.5 Gbps port the WiFi 7 - 6 GHz speeds are much faster than when connected to a 10 Gbps port on the same modem."

This is an interesting addition. I'll try connecting the router via a regular 1Gbps twisted pair cable instead of fiber optics for testing. And not to the combo port, but to a regular one.