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AC68U Throughput

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galambert75

New Around Here
Hello everyone!

I'm new to the forum. Hoping someone in the round might have some prior experience with the AC68U, which I'm (still...) using as my main home router.

The AC68U appears to be the bottleneck limiting my internet bandwidth. I have a 500 Mbps FTTH connection to Movistar (Spain). When I run speed tests (Fast.com, Speedtest.net, Provider speed test) using a LAN cable I'm only getting about 110-130 Mbps. For testing purposes, I've tried bypassing the AC68U and running the tests directly on the ISP router. In this case I do get the 500 Mbps.

Background:
  • The Movistar ISP router is only used as a modem: Movistar --(fiber)--> ISP router --(UTP)--> AC68U -- (WiFi / UTP) --> End devices
  • The AC68U is running the latest version of Asuswrt-Merlin + AMTM with several add-ons (more on that below)
  • WAN connection type on the A68U = PPPoE
  • In the "Network Map" section of the AC68U, the WAN port which connects to the Provider router shows Status = 1 Mbps
  • These are the add-ons enabled on AMTM:
    • Skynet (v7.4.5)
    • YazFi (v4.4.3)
    • scribe (v3.2.0)
    • nsrum (v30.4.0)
    • connmon (v3.0.2)
    • scMerlin (v2.4.0)
    • uiScribe (v1.4.5)
    • AdGuardHome (v1.6.2)
    • Entware packages
    • LED control
    • Swap file /mnt/rt68u_flash 2.0G
I assume the AC68U should support 500 Mbps throughput speeds.
  • Any thoughts on what could be causing the bottleneck?
  • Would disabling some add-ons improve the situation? If so, which?
  • Is it simply a case of hardware limitation?
Thanks in advance!

Rob
 
Last edited:
You run too many scripts on this older model 256MB RAM router and your PPPoE connection is incompatible with NAT acceleration. Your ISP provided router is perhaps much faster hardware device and it may also have better Wi-Fi. Your RT-AC68U is >10 years old model with hardware limitations.
 
You run too many scripts on this older model 256MB RAM router and your PPPoE connection is incompatible with NAT acceleration. Your ISP provided router is perhaps much faster hardware device and it may also have better Wi-Fi. Your RT-AC68U is >10 years old model with hardware limitations.

Thank you for the quick reply!

After my original post I found a thread where users do report getting higher throughputs with the AC68U. I take it that the difference in this case is the PPPoE?
 
  • These are the add-ons enabled on AMTM:
    • Skynet (v7.4.5)
    • YazFi (v4.4.3)
    • scribe (v3.2.0)
    • nsrum (v30.4.0)
    • connmon (v3.0.2)
    • scMerlin (v2.4.0)
    • uiScribe (v1.4.5)
    • AdGuardHome (v1.6.2)
    • Entware packages
    • LED control
    • Swap file /mnt/rt68u_flash 2.0G
That's an awful lot of add-on scripts the router is running. Have you tried, as a troubleshooting step, doing a hard factory reset then a manual configure (without reloading any saved config file, not having USB drive attached) and then doing a speed test from a computer wired to the router? Having all those scripts running along with a USB drive attached could be overtaxing the router.

I ran a RT-AC68U with only YazFi and YazDHCP add-on scripts for a time on a Fiber 500mb/500mb line. While the router's built in speed test always reported incorrect speed, a wired PC often reported close to or at 500mb up/down speed (when a good speed test site was used).
 
The AC68U is capable of much more than 110-130 Mbps, even with a PPPoE connection. But that's using an Ethernet cable, not via WiFi.
The bottleneck is the WiFi. What WiFi client device are you testing it with?

Note: For those saying this is an old device and it can't cope, yadda yadda... well, then how come that even my old N-only Netgear WNDR3800 router (worse specs in every way compared to AC68U) can still do 300+ Mbps over PPPoE on cable with DD-WRT (software NAT)?
 
users do report getting higher throughputs

Your best option is freshly reset firmware, no TrendMicro involvement, no QoS, no Custom Scripts. If still not good - you have to upgrade your hardware.

AdGuard Home is heavy for this hardware. You perhaps don't need Skynet - the built-in firewall blocks all unsolicited connections by default. nsrum script is obsolete. All J scripts have limited support, the developer moved to different platform some time ago. You perhaps don't need connmon on FTTH.
 
The AC68U is capable of much more than 110-130 Mbps, even with a PPPoE connection. But that's using an Ethernet cable, not via WiFi.
The bottleneck is the WiFi. What WiFi client device are you testing it with?

Note: For those saying this is an old device and it can't cope, yadda yadda... well, then how come that even my old N-only Netgear WNDR3800 router (worse specs in every way compared to AC68U) can still do 200 Mbps over PPPoE on cable with DD-WRT (software NAT)?

I'm testing with an Ethernet cable, not via WiFi. I guess I'll just have to bite the bullet and start removing a bunch of scripts...
 
[...]your PPPoE connection is incompatible with NAT acceleration.[...]
My Asus RT-AC68U H/W ver. A1 runs fine with NAT Acceleration and PPPoE type WAN connection.

@galambert75, check that you have hardware acceleration enabled in Tools menu -> Sysinfo page (/Tools_Sysinfo.asp) -> Network section -> HW acceleration field .
1692890608293.png

If it isn't, check that LAN menu -> Switch Control page (/Advanced_SwitchCtrl_Content.asp) -> NAT Acceleration field is set to Auto.
1692890845171.png

Hardware acceleration is incompatible however with some other features, like AiProtection, that needs to route network packets through the CPU for inspection. You can withdraw the TrendMicro agreement in Administration menu -> Privacy page (/Advanced_Privacy.asp).

Maybe hardware acceleration is incompatible with QoS as well, but I'm not sure since I never tried it, and of course if you are using a vpn client for the whole network then that will also limit speeds.

If you cannot configure it as is, save the current configuration and jffs partition from Administration menu -> Restore/Save/Upload Setting page (/Advanced_SettingBackup_Content.asp) -> Save settings and Save buttons, make a hard factory reset, reconfigure just the basics and run the speedtest again.
 
With those speeds currently and with the near (ish) future in mind, the GT-AX6000 will be a huge upgrade to your network experience.

Of course, I'm anticipating WiFi 7 (gen 2) to be available within the next 5 or 6 months. If you can hold on for that (possible) timeframe, do so.
 
most probably its the add-ons , i still posses an ac68u and it is still delivering some thing like 480/120 on an isp 500/125 plan so no complaints
 
My Asus RT-AC68U H/W ver. A1 runs fine with NAT Acceleration and PPPoE type WAN connection.

@galambert75, check that you have hardware acceleration enabled in Tools menu -> Sysinfo page (/Tools_Sysinfo.asp) -> Network section -> HW acceleration field .
View attachment 52606
If it isn't, check that LAN menu -> Switch Control page (/Advanced_SwitchCtrl_Content.asp) -> NAT Acceleration field is set to Auto.
View attachment 52607
Hardware acceleration is incompatible however with some other features, like AiProtection, that needs to route network packets through the CPU for inspection. You can withdraw the TrendMicro agreement in Administration menu -> Privacy page (/Advanced_Privacy.asp).

That did it!

It was showing: "HW acceleration Disabled - incompatible with: IPTraffic"

After disabling IPTraffic under "Tools --> Other settings" as per this post, I'm getting 620+ download / 560+ upload (the ISP is overdelivering!)

All AMTM scripts are still running, but I did disable QoS.

So it looks like the old AC68U might still hold for a few more months, maybe even until WiFi 7 🙌

Thank you all for your kind support! You saved me hours of troubleshooting!
 
That did it!

It was showing: "HW acceleration Disabled - incompatible with: IPTraffic"

After disabling IPTraffic under "Tools --> Other settings" as per this post, I'm getting 620+ download / 560+ upload (the ISP is overdelivering!)

All AMTM scripts are still running, but I did disable QoS.

So it looks like the old AC68U might still hold for a few more months, maybe even until WiFi 7 🙌

Thank you all for your kind support! You saved me hours of troubleshooting!
glad to hear you'v solved the issue

the good old AC68u is one of asus's power hourses
 

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