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GT-AXE16000 Poor Ethernet Performance

Level 8
Hi all - I've done quite a bit searching on this topic, but haven't found a fix. I'm hoping that someone here can offer an assist!

Current setup:
Internet: Xfinity, 1200 down / 40 up
Cable modem: Arris S33
Router: GT-AXE16000

The main issue I'm seeing is very mediocre and unstable Internet speeds when connected via Ethernet (currently 10G Port, but I've tried other ports as well.)

In speedtests (, Speedtest app to local Comcast server), speeds start fast (just over 1Gbit) then immediately drop somewhere between 300-500Mbit before recovering a bit. In comparison, if my laptop is connected either directly to my modem or even to the 5GHz Wi-Fi network, I don't have any speed issues whatsoever and typically test around 1250-1300Mbit. I've actually noticed my gaming laptop typically speedtests faster with more stability on the 5GHz Wi-Fi network (160MHz channel) than it does Ethernet, which is both exciting and disappointing at the same time.

QoS is off, AiProtection is off, I've attempted switching the WAN port to one of the 10G ports, and I've factory reset it at least once in an attempt to fix the issue. No joy.

I did see a review from Tom's Hardware talking about slow Ethernet performance with the GT-AXE16000... If this isn't fixable, I may just switch over to an ET12 mesh system for my home rather than utilizing the GT-AXE16000 as my primary.

Thanks in advance!

Level 15
Yeah unfortunately I'm puzzled. Windows computer MSI GS65 Stealth Thin 8RE is connected with a short maybe 5 ft Cat 6 cable to a 2.5 GBps 5 port switch, Cat 8 2 ft to wall plug, in wall wiring to either 10 G switch, or 2.5 G to 10 G switch, then AXE16000 via Cat 6e wall cable (2004 install). (I forget what cable is connected from the wall to the AXE16000). I just tested with 1 Gb ethernet port @ "Multi" connections 742.36 down 2.36 up. When I go to ASUSwrt I still get about the same as the past, 1075.68 down 42.32 up. Sorry I did not check the Jumbo Frame before asking, mine went down also. "Single" also made it bad.


I stopped checking ethernet speeds after I set up my son's MacBook Pro 14" (2023) with a new to him OWC Thunderbolt Pro Dock. Initially I connected the ethernet port from this dock through 2 (or 3) 2.5 Gbps switches, to the 10 Gbps port on the AXE16000. He was interested in how significant this was and immediately ran some speed tests ( and got 1000+ down and at least 40 up. I have since replaced the switch in his room with a TRENDnet TEG-S762 and one of the in closet wall box 2.5 G switches with a TP-Link TL-SX1008. I verified that the signal goes directly through those two switches to the 10 Gbps port on the AXE16000 for 10 Gbps backhaul to the AXE16000. (I no longer get that annoying yellow color ethernet port on ASUSwrt saying my internet speeds can be improved! Since this is a huge upgrade from 2.5 Gb backhaul I didn't even bother to verify he's getting the same throughput because he already maxed out our service. All other routers/nodes and devices were not disconnected for these tests. All WiFi bands still on.

I should verify he's still capable of getting these speeds when he comes home tonight. There have been maybe a couple of firmware updates since...

I have the prior StarTech Thunderbolt 3 dock with 1 Gbps ethernet port. I installed the Thunderbolt 3 Intel driver from the Intel website. Connected the Thunderbolt 3 cable (that came with my wife's old MacBook which she returned) to the MSI GS65 Stealth Thin 8RE. Results 746.20 down 40.15 up. There's definitely something wrong at least with the dismal upload speeds. Intel's, ASUS's fault, or both?

Level 15
Here's the test from my son's MacBook 10 Gbps uplink to the AXE16000: 1070.83 down 41.83 up.

So I did have a couple of odd symptoms rear their ugly head, so I picked up an ET-12 to perform some testing to see if it's simply how my laptop is reacting with the router or if it's actually a router issue.

More to come...

Level 15
I found a security flaw that Intel is aware of, thinking it may resolve this I tried to update the computer, to no avail. I then bumped into this FAQ in MSI International webpage:

Network upload speed is limited to 1- 2 Mbps
The symptom happens on models which bundled with Killer Ethernet Controllers and has Killer Suite package version 1.6.xxxx - 1.6.1892 installed; To check the upload speed, please run the benchmark test here.

To fix the problem, it is mandatory to manually uninstall Killer Performance Suite from Control Center > Programs and Features, and then re-install the Killer Performance Suite 1.6.1893 or newer version.

More details here:

Gonna try this solution now...

Level 8

So as an update - My inconsistent Internet speeds have continued, but I've narrowed things down a bit.

Recently, I've tested connectivity on 2 different laptops using 2 different USB to 2.5Gbit Ethernet connectors. In order to isolate the AXE-16000 fully, I even swapped to an ET12 router and everything worked perfectly (as far as wired. Once you Mesh setup the ET12, other things pop up...)

Also, I've noticed this unstable connection primarily happens on any connections over 1Gbit. The 1Gbit connections are pretty stable, but once I move to the 10Gbit ports, or even the 2.5Gbit port (since I've also flipped WAN to a 10Gb in my testing, also my service with Comcast/Xfinity is 1200+) the inconsistencies begin. 

My decision was to return this router a second time to Amazon (5 star support on their end) and try for one more. If I get a 3rd AXE-16000 that has weird bugs, I'm done with it.

I got some new cables, 6a, to help but it does have a better transfer rating than the 6e.  As you noticed, I have been getting 1.6 to 1.8 Gbps on the wired 2.5 Gbs system port, from the 2.5 Gbs AXE 16000 port which is getting the data from a 2402 Mbps Wi-Fi system.   The 1.6 Gbps is probably due to the Wi-Fi transfer speed.

Hopefully, the new router works better, but for us, mixing different devices, such as Routers, makes it hard to even follow exactly what is going on.  If you system does become unstable above 1 Gbps then possibly it is a cable or some other component.

They have redone the Beta firmware, in case you did not notice.  I do not know it if would help, since I do not appear to need it.

Maximus Z790 Hero,
Intel i9-13900k
Intel BE200

Apologies if I created any confusion. Main point I was going for was that I was attempting to isolate pieces of hardware to see if it was the router or something connected to it. So far, it seems to be my router as other devices don’t have any issues when connected to other means of connectivity. 

Another thing I forgot to mention is I also tried Merlin firmware to see if that helped at all. No joy. Ended up going back to the current Asuswrt. I’ll definitely post updates once I receive the new AXE-16000 with hopefully better news!

I have been continuing my research and was wondering, do you show both Wi-Fi and Ethernet connections at the same time?  Mine was doing that I my transfer speed was around 500 Mbps using the same file.

I just did a test using the 2.5 Gbps ports on the Z590 and 690 motherboards and the two 10 Gbps ports on the AXE16000.



Maximus Z790 Hero,
Intel i9-13900k
Intel BE200

Hi Saltgrass - I've made sure that my Wi-Fi was off on my laptop while I was hardwired to the router, so I wasn't double-connected.

Unfortunate news... I received the brand new GT-AXE16000 and this one can't even get a WAN address from Xfinity. It just sits on "Your ISP's DHCP does not function correctly" no matter what I do. I've reset my modem several times, I've updated the firmware on the router (had it downloaded to my laptop), I've tried switching ports around, factory reset the new router, feels like I've tried everything. So I can't even test my Internet speeds because I can't even connect to the Internet with it! *Facepalm* I think I'm done with the GT-AXE16000... I've had nothing but bugs and problems with it and this one kind of takes the cake. I'm going to give it a day or two to see if there might be something going on with Xfinity, but I doubt it.