topic BT10 - WAN speed limited to ~250Mbps in Networking

BT10 - WAN speed limited to ~250Mbps

brightium — Thu, 09 Apr 2026 08:17:03 GMT

new BT10 on last firmware 3.0.0.6.102_39110

the WAN max download WAN speed is ~250Mbps on 1Gb down/ 250Mb up fiber

the same thing for both 1G/10G WAN connections, short CAT6 between the router and the media converter

while speed testing on download the CPU1 is maximized, on upload CPU4 maximized

changing the cable not solved the issue

reset to factory and minimum configuration not solved the issue

NAT hardware acceleration switch not exposed in switch settings like in older ASUS routers

old XT8 router is fine, speed test about 950/260

the CPU thing on BT10 appears to point to a NAT hardware acceleration problem that default to software

any recommendations?

regards, Jonathan

Re: BT10 - WAN speed limited to ~250Mbps

jzchen — Thu, 09 Apr 2026 10:37:58 GMT

Try installing 3.0.0.6.102_39106. Then try upgrading to the 3.0.0.6.102_39110 again. Firmware is getting complex maybe did not install correctly....

Re: BT10 - WAN speed limited to ~250Mbps

brightium — Thu, 09 Apr 2026 17:58:30 GMT

I will try...

It's possible to downgrade from 3.0.0.6.102_39110 to 3.0.0.6.102_39106? It's safe?

It will reset the router, or the router will need to be reset? If yes, the backup configuration file can be reused?

Any special procedure or thru the router GUI as usual?

Sorry for the questions, the router is active and the older one not in my possession anymore

Re: BT10 - WAN speed limited to ~250Mbps

Alex52 — Fri, 10 Apr 2026 02:46:22 GMT

Yes, it is safe to downgrade firmwares. The new firmwares have improved protection for your router to help prevent hacker attacks.

Be sure to do a factory reset after downgrading and again after upgrading to the new firmware. Don't use any saved configuration files. Set up manually.

You can use the web GUI to upload the older firmware after first downloading it from the ASUS firmware downloads site.

Re: BT10 - WAN speed limited to ~250Mbps

brightium — Thu, 16 Apr 2026 20:29:26 GMT

downgrading to 3.0.0.6.102_39106, resetting and configuring again didn't help, but the principle itself is fine 🙂

downgraded to 3.0.0.6.102_38991 which seems to be on same major version as the last one, reset, new configuration, verifying that the speed is good, firmware upgrade by the router itself (not by downloading on the PC), after that connecting the second AiMesh pair, confirming the speed again.

all good for now, just strange entries a few times per second on the log:

Apr 16 22:56:33 kernel: fifo_bitmap_by_startidx:
Apr 16 22:56:33 kernel: fifo_bitmap_by_startidx:
Apr 16 22:56:33 kernel: 0000: 00 00 00 00 00 00 00 04
Apr 16 22:56:33 kernel: 0000: 00 00 00 00 00 00 00 04
Apr 16 22:56:33 kernel: fifo_bitmap_by_startidx:
Apr 16 22:56:33 kernel: fifo_bitmap_by_startidx:
Apr 16 22:56:33 kernel: 0000: 00 00 00 00 00 00 00 04
Apr 16 22:56:33 kernel: 0000: 00 00 00 00 00 00 00 04
Apr 16 22:56:33 kernel: fifo_bitmap_by_startidx:
Apr 16 22:56:33 kernel: fifo_bitmap_by_startidx:
Apr 16 22:56:33 kernel: 0000: 00 00 00 00 00 00 00 04
Apr 16 22:56:33 kernel: 0000: 00 00 00 00 00 00 00 04