Slow Speeds on Newer Firmware

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A-A-Ron

New Around Here
Network Topology
FTTH Connection to ONT in basement
Speeds 1000Mbps Download and 750Mbps Upload.
RT-AC88U connects to ONT with cat6 cable.
Desktop connects to router Cat6


On older firmware 384.45xx entire network has access to full Gig speeds, usually test from fast.com at 800-900Mbps.
Ever since that firmware speeds drop down to 200-300Mbps for all devices on network. Wired and wireless.
Narrowed it down to be QoS bandwidth Limiter being enabled for some devices was the cause. On the newer firmwares if i disable that feature and manually reboot router full speeds return. If i re enable it speeds drop for the entire network, not just the devices set to have limited bandwidth.


Im currently talking to Asus try get resolved, have been for last 2months now.
Currently on their beta firmware version 3.0.0.4.386_39058 and issue remains.
They have most recently tried saying Nat Acceleration was the cause but its not confirmed by disabling it and rebooting router but speeds still slow..
see most recent response below...
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Please see the response from our R&D Team below.

After detailed review of this issue, we have found that the root cause is the conflict of whether process packet recognition.

To achieve the function of the Bandwidth Limiter, which in needs of recognition of each packet to throttle bandwidth. While NAT accelerator is a mechanism to speed up packet transition via by-passing the recognition process. Therefore, the two functions are conflicted in the process of packet recognition, users may only choose one function at a time.
=====================

They have also tried saying this is just how bandwidth limiter works, also not true bandwidth limiter should only effect devices set to have limited bandwidth and the rest of the network should remain as normal unrestricted. Comments from them on that below
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Please see below feedback from our HQ team.

Please advise the customer the older FW, which user didn't have issues with speed, is NOT the normal behavior.

In the older FW, the NAT accelerator was not correctly disabled when QoS Bandwidth Limiter was enabled. This will result in a "Potential issue" where packets of the limited device passes the NAT accelerator by accident (maybe CPU was too busy to limit the option), when it happens, the device will NO LONGER be limited, which could also be a big problem.

To help us to further verify the issue in the lab, may suggest using the older FW, enable the QoS Bandwidth Limiter feature, then turn off the router and turn it back on again. This will correctly shut down the NAT Accelerator option, which should then result in the same behavior as new FW would behave - while QoS bandwidth limiter is on and NAT accelerator is off, ALL devices will have slower speed.

We do apologize for the limitations of these two functions and may suggest selecting the feature that needed the most (General Speed vs Bandwidth Limitation).
====================

If i downgrade to older firmware anything from this version or earlier 384.45xx everything is fine with bandwidth limiter enabled and all but if update to anything newer than that and network wide slow speeds 60% loss..

Has anyone else had this issue or if you have the speeds close to mine can you replicate it?

Also am i wrong for believing that the function of Bandwidth Limiter is to ONLY limit speeds for the selected devices and then leaving full speeds for the rest of the network NOT Limit the entire network to speed i can not set and then limit the devices i have put on its list to the speeds i set them to?
 

dave14305

Part of the Furniture
As ASUS correctly states, NAT acceleration must be disabled for the router to even identify which packets belong to devices that you want bandwidth limited. You don’t mention which router model, but Many models cannot perform above 200 Mbps without NAT acceleration enabled due to CPU constraints.
 
Last edited:

ColinTaylor

Part of the Furniture
The problem is that NAT acceleration is either on of off for the whole router not individual clients. If it is off you will see exactly the slower speeds you are seeing because the router becomes CPU-limited.

The difference is obvious with Traditional QoS vs. Adaptive QoS. Traditional QoS must disable NAT acceleration while Adaptive QoS doesn't.

I don't know how the Bandwidth Limiter works but from the response you got from Asus it sounds like they are saying it works like Traditional QoS, i.e. it turns off NAT acceleration. Asus seem to be suggesting that Bandwidth Limiter was "broken" in the earlier firmware or you didn't power off/on the router after making changes to QoS. This power off/on requirement is a known old bug.
 

A-A-Ron

New Around Here
The problem is that NAT acceleration is either on of off for the whole router not individual clients. If it is off you will see exactly the slower speeds you are seeing because the router becomes CPU-limited.

The difference is obvious with Traditional QoS vs. Adaptive QoS. Traditional QoS must disable NAT acceleration while Adaptive QoS doesn't.

I don't know how the Bandwidth Limiter works but from the response you got from Asus it sounds like they are saying it works like Traditional QoS, i.e. it turns off NAT acceleration. Asus seem to be suggesting that Bandwidth Limiter was "broken" in the earlier firmware or you didn't power off/on the router after making changes to QoS. This power off/on requirement is a known old bug.
Router has been rebooted several times on older firmware and everything remained the same.. so it wasnt that..

But i manually downgraded for more testing, manually turn off NAT Accelerator and i get slow speeds just like newer firmware. Re-enable NAT Accelerator on older firmware and i get Full speeds back to desktop and devices i have set in bandwidth limiter have limited speeds like i want still.. Also noticed it says "CTF (Cut Through Forwarding) is enabled" on the same line as NAT Acc on older firmware when NAT Accelerator is enabled. Not sure if that may have something to do with it being this way on older firmware. Newer firmware i see no mention of that "CTF"

To me the older BROKEN firmware seems better entire network had full Gig speeds and the selected devices i wanted to have limited speeds had exactly that.. I just wanted to update for the security patches and all.. Looks like i may stay on broken firmware.. Unless ASUS will i guess re break it so it works better (how i want it to work)
 

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