RT-AC1750_B1 slow wifi speeds on gigabit fiber connection

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New Around Here
Hi there!

I have a RT-AC1750_B1 running the latest Merlin build, and I just got a new gigabit connection, but the wireless speeds are much slower than expected (around 1/3).
  • Connecting directly to fiber modem (wired): 900Mbps down/up
  • Fiber modem wired to RT-AC1750_B1 WAN port & wired connection from router: 900Mbps down/up
  • 5ghz wifi connection: 300Mbps down/up
    • QOS is off
    • AiProtection is off
I've tested the wifi on two separate devices, one 802.11ac and the other 802.11ax/Wifi6, and the results are identical.

I know the RT-AC1750_B1 has a max throughput of 1300Mbps at 5ghz, and this is a "theoretical" max, but shouldn't my wifi speeds be closer to the 900Mbps mark?

Are there any other settings I can try? Am I wrong to expect higher wifi speeds with an 802.11ac router?

Any advice is appreciated!


Part of the Furniture
Try the Asus firmware.
By "latest" merlin do you mean 384.19? If so say so! Latest is not specific!
If you are on Merlin 384.19 drop back to 384.18, factory reset and configure manually. And don't use a VPN client while testing!


Part of the Furniture
Are the test devices handhelds? Can you test with a plugged into AC power laptop?


New Around Here
All are computers/laptops and plugged in.

Interestingly enough, we tested a different router (Linksys Wifi 6), and the result was the exact same.

Is there something that would limit the wireless connection to 300Mbps? Should I be able to get close to 1000Mbps with one machine connected to a router with a 1 gig WAN (assuming no other devices on the network)?


Very Senior Member
Are your clients 2x2 or 3x3 devices?


New Around Here
One is 95% 3x3 (2019 MacBook Pro) and I assume the other is (Intel Wi-Fi 6 AX200), but I'm not sure as to how I check/verify.


Very Senior Member
What does the router and client report for link speeds? Seems like I remember reading a few threads regarding issues with the Intel cards and driver issues. Might want to look into that as a possibility.


New Around Here
The link speeds seem fine.

On another note, when I put in the gigabit WAN connection, the CPU maxes out when a wired connection reaches 600Mbps (vs 900+ direct from the modem). I think this thing isn't fast enough to handle the bandwidth...


New Around Here
Wireless on that is 1300Mbps on 5G in full duplex, sadly wifi devices connect in half duplex so your only gonna get half that so optimal you should see 650Mbps IF you receiving device has the proper antenna setup 3x3 and has the RAM, CPU and Drive storage speeds to support faster speeds. TBH the avg i see for 5G (Wifi5/AC) wifi is about 400Mbps (i work for an isp tech support do quite a few router setup on all brands)
I have not tested too many wifi6/AX routers yet.

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