RT-AC68U Slow LAN

petecool

New Around Here
Hi, I am having issues with wired connection to my pc from RT-AC68U router. I have a 1000/50 fiber and tested speeds without router(directly from ISP box to pc) and I am getting 940/48. The issue is obviously to do with this Asus router. When I use the LAN through router I am only getting 289/47. I was previously using 2019 firmware and updated to the latest 3.0.0.4.386_49703 firmware resulting in only a slight increase in speed. Before I was getting 170-200 download but this is because I had older firmware, Aiprotection and QoS on. Since these changes I have gone from 170-200 average to 250-290. I have looked through all the forums and still cannot find a fix for my issue.

Current settings:
QoS - off
AiProtection - Off and withdrew from trend micro website tracking in privacy settings but have not withdrawn from "For Account Binding, DDNS and Remote connection(ASUS Router APP/Lyra APP/AiCloud/AiDisk):" I am unsure if it will cause any issues if I withdraw from this so I have left it as is.
Jumbo Frame - Disabled
HW Acceleration - Disabled (Unsure if this setting needs to be on or off)
STP - I am trying to find this setting but it is not showing up in LAN>Switch control. All I see is Jumbo Frame and Nat Acceleration.

If anyone can guide me where to find STP or how to make this setting show in switch control page so I can test it in OFF setting (I assume by default it is set to ON but unsure about this). Do I have to revert to older firmware to show this setting or use merlin? I did read some other posts and other users fixed their LAN speeds by disabling STP. I am unsure on what to do from here on, I am close to just buying a new router because I have been paying for 1000/50 for months and not achieving these speeds. I understand this router is quite old now but it should be achieving the full LAN speed.

Update: I have enabled HW Acceleration (CTF (Cut Through Forwarding) is enabled) and my speeds are now 350-370 on average which is a decent increase but still no where near the 940 I was achieving directly from the ISP box to pc.
Update 2: I have updated firmware from stock asus to 386.7_2 Merlin and now see the option for STP. I have tested speeds with it disabled and it has had no effect on the speeds. All avenues have been exhausted based off the research I have done with other users in my situation and I am unsure on what to do from here on.


I have had a look and can see that my NVRAM usage is quite high at 64519 / 65536 bytes, I am unsure if this has any impact on speeds though. I came across this comment after a user tried everything and found that a hard reset fixed his issue: "However, after some trial and error, I think I got everything working (or at least working well enough, into the high 800 MBps). I did a "hard reset" (NVRAM reset) on the router. I thought I did this before and didn't have much luck, but either this time was successful (or I am misremembering) - but "nuking" all the settings and starting from square 1 seems to have mostly resolved the issue." Taken from here: https://www.snbforums.com/threads/troubleshooting-slow-lan-speed-on-rt-ac68u.62083/

Is a hard reset the same as a factory reset? I have yet to do a factory reset since buying the device many years ago. This seems to be the last option which could potentially fix the issue.
 
Last edited:

bennor

Very Senior Member
When I use the LAN through router I am only getting 289/47.
How are you testing the speed? Are you testing the WAN speed or LAN (Client to Client) speed? Are you testing the internet speed using the router GUI's speed test (Adaptive QoS > Internet Speed)? If so, there are various complaints about that speed test reporting incorrect speeds. Typically reporting half of the actual speed when one tests the internet speed from a Gigabit wired PC connected to the RT-AC68U.

Sometimes a hard factory reset can fix certain issues or problems.
[Wireless Router] ASUS router Hard Factory Reset - Method 1
 

petecool

New Around Here
How are you testing the speed? Are you testing the WAN speed or LAN (Client to Client) speed? Are you testing the internet speed using the router GUI's speed test (Adaptive QoS > Internet Speed)? If so, there are various complaints about that speed test reporting incorrect speeds. Typically reporting half of the actual speed when one tests the internet speed from a Gigabit wired PC connected to the RT-AC68U.

Sometimes a hard factory reset can fix certain issues or problems.
[Wireless Router] ASUS router Hard Factory Reset - Method 1
I am testing from router to pc ethernet cable internet speed not local network speed. I am testing via speedtest.net website and selecting the same server every time. I also tried the built in speed test and I found it to be giving unreliable results.
 

petecool

New Around Here
I found the issue after 2 days of messing around. I use TP Link powerline over ethernet adapter so I have a few different ethernet cables. The cable from the ISP box to router was using CAT 5, and cable from router to powerline adapter was also CAT 5. I didn't think of it because I thought I would have at least used CAT 5E cables. I tested a CAT 5E cable from router directly into PC and was about to achieve 930mbps which is what I wanted but will have to have a wire going across the floor to the router. I cannot use the powerline over ethernet adapters even though it is rated to 1000mbps because my house powerline from the router to the room is unable to achieve these speeds because on TP Link "Powerline Rate" test it says it has something to do with the wiring of my electrical and the transmission capacity not being able to reach full speeds.
 

Justinh

Regular Contributor
Yeah, powerline adapter ratings are meaningless to the consumer, in my opinion. I have a 2000Mbps adapter and get ~100Mbps. (I've tried three brands and two technologies w/o much difference.) If you look at reviews, results are all over the place but none even close to the rating.
 

Sky

Regular Contributor
I found the issue after 2 days of messing around. I use TP Link powerline over ethernet adapter so I have a few different ethernet cables. The cable from the ISP box to router was using CAT 5, and cable from router to powerline adapter was also CAT 5. I didn't think of it because I thought I would have at least used CAT 5E cables. I tested a CAT 5E cable from router directly into PC and was about to achieve 930mbps which is what I wanted but will have to have a wire going across the floor to the router. I cannot use the powerline over ethernet adapters even though it is rated to 1000mbps because my house powerline from the router to the room is unable to achieve these speeds because on TP Link "Powerline Rate" test it says it has something to do with the wiring of my electrical and the transmission capacity not being able to reach full speeds.
It could be the Powerline adapters are on different circuit breakers, they could be on different electrical phases, maybe also power adapter / charger warts on the circuits — especially at the "receiving" end(s). It seems pretty common to have a 30+% loss of speed over Powerline Ethernet even on the same circuit breaker, and sometimes the circuit breakers themselves are an issue see: SNB Troubleshooting Your Powerline Network [archives]. Also, every device using that Powerline is on the same physical piece of cable, unlike an Ethernet-connected desktop that 'owns' the run it's on until it gets to the switch or router. I'm not aware of speed problems associated with AiProtection, more a privacy issue; is this something you've seen here somewhere?

According to my ISP (Comcast/Xfinity), I have 1.4Gb over cable but it maxes out around 950Mb at and from the DOCSIS 3.1 modem and stays pretty close to that through the firewall/router to the Gb switch and out to my Ethernet wired desktops — that's through roughly 150' of plain Cat 5 Ethernet. A lot of the time it's down in the sub-500 range which comes from issues on the plant-side of the B-box at my site (other branches, other customers with bad equipment or improperly attached modems, etc.). The Wi-Fi clients are slower of course. In the end I don't care anymore what the "speed" is as long as everything works as-expected. It's kind of like the computers — if I see results on the screen instantly after tapping [enter], that's as fast as I can actually use; waiting for a computer to compute has mostly disappeared save engineering and A/V work.

BTW, thanks to everyone for the many Powerline discussions here on SNB. They are proving very helpful for my site assessments considering this as one of the options.

Sky
 

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