Question TP-Link AC5400 - Internet Speed Enigma

[RhoXS]

I have successfully worked through the issues I discussed in two other recent threads. At this point I found there is no need to replace the Comcast modem with a new Motorola modem and I now have reliable access to the TP-Link router setup (apparently via a firmware update). The Comcast modem is in Bridge mode, its wireless functions are inactivated, and I have a much more reliable wireless network with a much stronger and consistent WiFi signal throughout my house (the raison d'etre for this entire exercise). The only problem remaining is a very inconsistent and much too slow internet speed, with respect to what it should be, apparently due to something associated with the TP-Link AC5400.

If I connect my desktop PC direct to Port 1 on the Comcast Modem (in Bridge Mode) via an Ethernet connection, it appears I can reliably achieve >900 mbs (I pay for 1,200 mbs service). However, if I connect my desktop, via the same Ethernet connection, to the TP-Link AC5400, and connect the AC5400 "Internet Port" to the Comcast modem Port 1, internet speed varies considerably, and is mostly <=500 mbs and frequently 250 - 300 mbs. Frequently the reported speed is so close, if not exactly on, 300 mbs or 500 mbs, it appears something is intentionally limiting the speed to that.

Now the real WTF. If I reboot the TP-Link AC5400 via the "Reboot" button in its setup dialog, and do a speed test run immediately after the reboot finishes, the speed test will always report >900 mbs. However, waiting even just a few minutes after the reboot finishes will cause the speed test to land at almost exactly 500 mbs and sometimes less. I would certainly appreciate insight into this phenomena. My instinct tells me this has something to do with the TP-Link AC5400 as direct connecting the desktop to Port 1 on the Comcast modem will consistently yield >900 mbs.

I should mention, in the TP-Link setup dialog, under Advanced/IPv6, by default, IPv6 was not turned on. I turned it on but did not change any of the many associated setting as I was then in well beyond my pay-grade. Doing this also seemed to have no obvious effect on anything else.

So, what settings should I be looking at in the TP-Link device that might be limiting the internet speed? The TP-Link AC5400 is advertised as a "Gigabit Router" so it should be able to consistently provide the >900 mbs available from the Comcast modem.

Thank you for the responses to my recent previous threads. The responses collectively helped considerably getting this far.

UPDATE: After a bit of bouncing around in the TP-Link AC5400 setup dialog, under Advanced/IPv6, I changed "Dynamic IP" to "Pass-Through (Bridge)". That appears to now cause the speed tests to consistently report much higher speeds. Still too slow for a supposedly 1200 mbs connection as the speeds, depending on the test run, vary between 650 and 950 mbs, but this did seemingly accomplish something.

 

[Tech Junky]

There's probably some software item turned on that's inspecting packets.

 

[lantis3]

You have been told TPlink AC5400 WAN port speed is 1Gbps. You will never get anything beyond that even if your subscription speed is 1.2Gbps unless you upgrade your router and your PC's NIC. 950Mbps is probably the best you can get now.

And even if you upgrade your own router, you have to connect WAN port to modem gateway's 4th port marked with an orange line.

https://www.cox.com/residential/support/technicolor-cgm4331.html

 

[RhoXS]

you have to connect WAN port to modem gateway's 4th port marked with an orange line.

My error, I remember reading port 1 but, obviously, I was wrong. I just changed to the port 4 but that I do not see any change.

You have been told TPlink AC5400 WAN port speed is 1Gbps.

I am well aware I was told the AC5400 is limited to 1 gps and I am well aware of the devices specs. However, since my service is at least supposed to be 1.2 gps, I DO NOT expect the actual speed to be many 100s mbs less than 1 gps, even, not infrequently, as low as 250 mbs. That is exactly the problem I am trying to solve. Nevertheless, thank you for the reminder again.

 

[VirtualLarry]

Still too slow for a supposedly 1200 mbs connection as the speeds, depending on the test run, vary between 650 and 950 mbs

950 mbit/sec is the effective limit of IP communications over 1GbE.

You need to be using 2.5gbe to get the 1200.

 

[VirtualLarry]

If you're maxing out significantly below that (500mbit or 300mbit), then your hardware NAT has been disabled, in favor of more (deluxe feature) packet-processing in software.

Disable bandwidth control, VPN, TrendMicro A/V, monitoring, etc.

 

[lantis3]

"at least supposed to be 1.2 gps" actually is at most.

And 1Gbps port only guarantees the speed between you and your ISP, anything after ISP is not guaranteed.

If you have a spare or unused PC with 2NICs, you can install firewall like pfsense to test if TPlink is really the culprit to cause the slowdown.

 

[bba-tcg]

I have successfully worked through the issues I discussed in two other recent threads. At this point I found there is no need to replace the Comcast modem with a new Motorola modem and I now have reliable access to the TP-Link router setup (apparently via a firmware update). The Comcast modem is in Bridge mode, its wireless functions are inactivated, and I have a much more reliable wireless network with a much stronger and consistent WiFi signal throughout my house (the raison d'etre for this entire exercise). The only problem remaining is a very inconsistent and much too slow internet speed, with respect to what it should be, apparently due to something associated with the TP-Link AC5400.

If I connect my desktop PC direct to Port 1 on the Comcast Modem (in Bridge Mode) via an Ethernet connection, it appears I can reliably achieve >900 mbs (I pay for 1,200 mbs service). However, if I connect my desktop, via the same Ethernet connection, to the TP-Link AC5400, and connect the AC5400 "Internet Port" to the Comcast modem Port 1, internet speed varies considerably, and is mostly <=500 mbs and frequently 250 - 300 mbs. Frequently the reported speed is so close, if not exactly on, 300 mbs or 500 mbs, it appears something is intentionally limiting the speed to that.

Now the real WTF. If I reboot the TP-Link AC5400 via the "Reboot" button in its setup dialog, and do a speed test run immediately after the reboot finishes, the speed test will always report >900 mbs. However, waiting even just a few minutes after the reboot finishes will cause the speed test to land at almost exactly 500 mbs and sometimes less. I would certainly appreciate insight into this phenomena. My instinct tells me this has something to do with the TP-Link AC5400 as direct connecting the desktop to Port 1 on the Comcast modem will consistently yield >900 mbs.

I should mention, in the TP-Link setup dialog, under Advanced/IPv6, by default, IPv6 was not turned on. I turned it on but did not change any of the many associated setting as I was then in well beyond my pay-grade. Doing this also seemed to have no obvious effect on anything else.

So, what settings should I be looking at in the TP-Link device that might be limiting the internet speed? The TP-Link AC5400 is advertised as a "Gigabit Router" so it should be able to consistently provide the >900 mbs available from the Comcast modem.

Thank you for the responses to my recent previous threads. The responses collectively helped considerably getting this far.

UPDATE: After a bit of bouncing around in the TP-Link AC5400 setup dialog, under Advanced/IPv6, I changed "Dynamic IP" to "Pass-Through (Bridge)". That appears to now cause the speed tests to consistently report much higher speeds. Still too slow for a supposedly 1200 mbs connection as the speeds, depending on the test run, vary between 650 and 950 mbs, but this did seemingly accomplish something.

You could use the routing functions of the Comcast modem and use the TP-Link as a wireless AP. That way, you could use the 2.5 Gbps port for your desktop while still getting the better wireless coverage of the TP-Link,

 

[Tech Junky]

https://static.tp-link.com/2019/201901/20190110/1910012411_Archer%20C54002.0_UG_REV2.2.0.pdf

Chapter 8 is where your slowness is likely to occur.

 

[RhoXS]

You could use the routing functions of the Comcast modem and use the TP-Link as a wireless AP. That way, you could use the 2.5 Gbps port for your desktop while still getting the better wireless coverage of the TP-Link,

I started out simply to change the SSIDs the Comcast modem uses. The Comcast modem uses the same SSID for both 2.5 & 5 Ghz bands. One of my devices is an electronic door lock that only uses the 2.4 GHz band but refuses to reliably remain connected to it. The manufacturer suggested that they have seen these issues when both SSIDs are identical. I really did not buy into their explanation but I decided to change the SSIDs anyway. Annoyingly, the Comcast modem setup dialog now locks one out of changing the SSIDs (it did not do this previously) unless one loads an app on their phone. I was not comfortable doing that so I decided to finally put the Comcast device in Bridge mode and use the TP-Link AC5400 I bought 4 years ago and was still in the shrink wrapped box. I was looking for an excuse to do this for a number of years to improve the WiFi system and now I had one.

Changing "Dynamic IP" to "Pass-Through (Bridge), as I explained somewhere above made a major difference. Now (at least since earlier this afternoon) I am reliably seeing between 600+ and 900+ mbs. I fully understand I can never see >1.0 gps because that is all the router is rated for. However, since the service is advertised at 1.2 Gps I would still expect to see a minimum somewhere near or slightly over 900 mbs and, indeed, the speed tests sometimes do get slightly over 900 mbs. BTW, as I previously explained, plugging my desktop directly into the Comcast modem consistently provides >900 mbs. Therefore, there is(are) some setting(s) associated with the TP-Link device that is causing it to run so much slower.

 

[bba-tcg]

... Therefore there is(are) some setting(s) associated with the TP-Loink device that is causing it to run so much slower.

Which was the reason for my suggestion.

You might see if QoS is enabled on the TP-Link.

 

[RhoXS]

Which was the reason for my suggestion.

You might see if QoS is enabled on the TP-Link.

Thanks. QoS is not something I was familiar with but I just did check that and did a bit of looking to see what it is. There is not anything obvious to enable/disable it but there is a dialog to set priorities. All day, since I changed "Dynamic IP" to "Pass-Through (Bridge) this morning, speeds have been consistently above 500 mbs and sometimes well above that, so I am not sure priorities matter. In any case I set gaming and chatting to Low and Streaming/Surfing to high.

I certainly do appreciate the suggestion.

 

[lantis3]

How to set up QoS using TP-Link Wi-Fi Router (new designed blue UI)

How to set up QoS using TP-Link Wi-Fi Router (new designed blue UI)

www.tp-link.com

So for this router if QoS is enabled then NAT Boost will be disabled. Apparently the CPU's power can only handle either QoS or NAT boost, not both at the same time. So if you enabled QoS then router's NAT performance will be affected.