ASUS RT AC68U slow download speeds

[Boo]

I have the Comcast Xfinity internet 600/20 plan and using ASUS RT AC68U with Merlin.
When I did a speed test behind the router, I am getting 200/20 speeds. But when I am connected directly to the modem, I will get close to 600/20.
I think the router is my problem and how do I fix it?

 

[bennor]

Are you using (or have used) any of the AiProtection options on the Asus router? Its a common issue some have experienced if one has enabled the AiProtection to see a speed drop. The general workaround is to disable or turn off AiProtection and then access the Privacy page under Administration and Withdraw from any listed options on that Privacy page.

 

[Boo]

Are you using (or have used) any of the AiProtection options on the Asus router? Its a common issue some have experienced if one has enabled the AiProtection to see a speed drop. The general workaround is to disable or turn off AiProtection and then access the Privacy page under Administration and Withdraw from any listed options on that Privacy page.

I have app analysis off, QoS off, classification, web history off. Withdrew under privacy page under adminstration. Still nothing worked.

 

[Boo]

Are you using (or have used) any of the AiProtection options on the Asus router? Its a common issue some have experienced if one has enabled the AiProtection to see a speed drop. The general workaround is to disable or turn off AiProtection and then access the Privacy page under Administration and Withdraw from any listed options on that Privacy page.

I disabled STP under LAN and seem to have gained the maximum speed of my provider. Do I need STP if I am using only 1 router?

 

[bennor]

I disabled STP under LAN and seem to have gained the maximum speed of my provider. Do I need STP if I am using only 1 router?

No idea if Spanning-Tree Protocol needs to be enabled or not. It appears it's default setting is on/enabled. One may need to reboot their router after turning off AiProtection and Withdrawing from the Privacy.

 

[itpp20]

STP should be off.

 

[BiggAW]

I had this issue when I moved and got 500mbps fiber, up from 150/10 cable. I was getting around 250/350. I found that changing the LAN-Switch Control NAT Acceleration setting from Disable to Auto fixed the problem and now I get over 510mbps in both directions.

 

[stalker780]

Do everybody get different down/up wireless speeds on their AC68U?

I have 1Gbit channel and LAN tests always show ~950/950Mbit.

But Wireless 5G download speed is always about 150-250Mbit lower than upload.
Tried different channels and bandwidths. Use ch104/80Mhz. Some configurations work slower, some faster, but download is always lower than upload.
Checked on Samsung S21+ and PC integrated AX210. Both devices show same results.

I have AC68P with Merlin 386.11 firmware. HW acceleration: Enabled (CTF + FA). Hard reset does not help.

What I have noticed, download test utilizes less CPU (60%) than upload (90%).

Also checked my main AX86U. It is located in a different room, but it shows down/up speed ~500Mbit. Difference is usually around 20-30Mbit.

This is not critical. I am quite satisfied with this good old solid device. Just curious if there is a way to make download speed same as upload ~700Mbit.

 

[L&LD]

This 9-year-old model was never meant for 1Gbps wireless speeds. The variability depends on the client device too.

 

[KGB7]

Best speed I could achieve in AC68U router on 5Ghz band is 430Mbps. Go to AiMesh settings, System Settings and enable Ethernet Backhaul Mode. This will give you an additional 50-100Mbps over wifi on 5Ghz band.

At the end of the day, you'll have to test on 10 different servers to see which once works the best in your area.

 

[SevenFactors]

/////* EDIT:*/////

After much tinkering with the router's WIFI settings I've been able to once again hit download/upload speeds equal and beyond the ISP advertised speeds. The difference is indeed meaningful across all WIFI devices. I've been testing this for the past couple of days and the difference is indeed among the following 2 settings. With them Enabled all is well. With them disable, the issue comes back.

The settings are found under Wireless/Professional

Optimize AMPDU aggregation: Enable
Optimize ack suppression: Enable

I've attached a picture of the overall settings.

I hope this is of help to anyone experiencing the same issues.
/////* END EDIT:*/////

........
Hello. I too am on this camp. I have xfinity and a RT-AC68U.
I've a much simpler broadband package 400/10

What I think the issue could be
I have come to think that perhaps the issue is the wireless driver.

Issue
When I first got this xfinity package the router was running Merlin 386.7

-*All wireless connection are 5GHz band AC devices.*-
-*Broadband tests: fast.com and speedtest.net*-

Back then I was able to get over 400Mbits down and over 10Mbit up.
Results like 400-480 down and 10-18 up. on all devices be it wired or wireless.

After upgrading to Merlin 386.11 now I can only get such results on wired devices. At its best wireless devices seem to be capped at around 200/8,10 yet most times when I run tests, the down speeds don't go any higher than 130Mbits and at times it is much lower like around 50-80.

NAT Acceleration is set to Auto and reads CTF (Cut Through Forwarding) is enabled

I'm not using a mesh network here, just the one router which connects directly to a dumb cable modem; nevertheless I did enabled Ethernet Backhaul Mode. Nothing really changed.

Some Back Story / Is this a sign the RT-AC68U is too old/dying?
I do remember that when I installed 386.10 the router started to report that it was running out of memory. I did some research here and reset the router and reconfigured everything by hand. Everything was working fine after that. No more memory nagging till today.

As of now the router is as plain as possible. I only have set some static IPs.

Normally I would be using a VPN client, more static IPs, YazFI, media server. As of now I don't because I don't want to run into more memory issues.

In the case this is the best RT-AC68U can do from now on (wireless speeds wise and memory wise), what would be the next best merlin compatible router upgrade? Future-proof, with plenty of memory to handle future merlin firmware upgrades, static IPs, YazFi, VPN client/Server and media server and still run smoothly!?

I was looking at the RT-AX88U_PRO as it seem to be the latest on Merlin's list.

Any input would be greatly appreciated.