Speed Test Upload Limit RT-BE88U

[nickp85]

*Update: I am using the latest Merlin firmware. Could someone move this into the Merlin forum if appropriate?

I am using an RT-BE88U router with the 10G port as my WAN port. The link is recognized as 10 Gbps and I have 2 Gbps service from my ISP. When running a speed test using the tester inside the router firmware from Adaptive QoS > Internet Speed, I am rate limited to 1 Gbps upload. I thought this was my ISP for months but I now have a machine wired to the router with a 2.5Gbps NIC. I ran the same speed test from a Windows machine to the same server on Speedtest and I get around 2 Gbps download and 2 Gbps upload as expected.

I would think the speed test directly from the router would be most accurate but upload appears to top out at 1 Gbps no matter what. This has been going on since I upgraded to this router and switched my ISP back in January. I'm not using QoS or any of the router's feature that would typically slow down speed.

Is there some kind of bug in the speed test implementation of the firmware?

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RT-BE88U

3006.102.4

Sat May 10 15:59:43 UTC 2025 root@0c35ade

0.0.0.6

wl0: Dec 19 2024 15:27:11 version 17.10.369.39012 (r839077) BSPv1W13 wl1: Dec 19 2024 15:27:11 version 17.10.369.39012 (r839077) BSPv1W13

 

[ColinTaylor]

I would think the speed test directly from the router would be most accurate

Your assumption is incorrect. There are hundreds of posts here noting that the inbuilt speed test (on all Asus models) can become CPU limited on high speed connections. The only accurate test is from a LAN client.

 

[AnClar]

The routers can potentially be affected by CPU bottlenecks. That said, my GT-BE98 pro on a 5gig connection seems to give fairly reasonable results. The router is behind an AT&T fiber gateway set in passthrough mode.