TP-Link Archer C7 v2 -- highly inconsistent download speeds

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vdanilchenko
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Joined: 08 Oct 2016
Posts: 8

PostPosted: Sat Oct 08, 2016 23:33    Post subject: TP-Link Archer C7 v2 -- highly inconsistent download speeds Reply with quote
Hi all,

I migrated to DD-WRT today on my Archer C7 v2 router, using the latest beta 'firmware-to-DDWRT-US.bin' build (the build from 10-06-2016). It all worked, except that my speeds now are highly inconsistent.

On a direct connection of my laptop the cable modem, Ookla speed test measures me at 180Mbits. However, through the router, I get anywhere from 2 to 90 Mbits. At different times, before and after reboots, I got 2Mbits, 25Mbits, 30Mbits, and 90Mbits.

I tried varying the installed services (e.g. enabling and disabling SSH, telnet, cron, etc.), rebooting, turning HTTPS and QoS support on and off, and I have found no consistent pattern in speed changes, except for the fact that the mere fact of changing configuration, seems to drop the speed for a while.

For instance, just now I measured speed at 90Mbps, with SSHD off and QoS on. I turned on SSHD, and it again measured at 90Mbps. I turned off QoS, and it measured at 13Mbps. I turned QoS back on (with 0s for uplink and downlink limits), and it measured at 17Mbps. I waited about 5 minutes, and speed went to 90Mbps, still only half of my total uplink speed. I waited another 5 minutes, and measured my speed at 3Mbps.

I also tried setting the uplink and download limits as per recommendations (160Mbits and 11Mbits respectively), to no effect.

Note that all this variability only affects the download speed. Upload speed remains very consistent in the 10-12Mbps range. I ran all the tests over gigabit Ethernet, but I replicated some of them over WiFi (AC1750) with the same result (my computer is 10 feet away from my router).

I did some googling and Wiki-trawling, but found nothing describing this sort of problem.

The bandwidth monitoring indicates that the rest of my household is consistently using less than 20 Mbps (out of 180), so clearly it's not them crowding out the bandwidth.

Does anyone have any idea on what to try, or how to diagnose, this behavior?

Thanks.
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vdanilchenko
DD-WRT Novice


Joined: 08 Oct 2016
Posts: 8

PostPosted: Sun Oct 09, 2016 0:36    Post subject: Reply with quote
By the way, I have also tried to set maximum priority for my IP in the QoS tab, and I am currently still getting 4Mbps.
B@R
DD-WRT Guru


Joined: 16 Apr 2011
Posts: 599
Location: Israel

PostPosted: Sun Oct 09, 2016 0:47    Post subject: Reply with quote
Try this service over LAN with and w/o QoS.

http://www.dslreports.com/speedtest

The speedtest.net may be very different from test to test and different servers. Sometimes it give me speeds over my ISP connection speed, sometimes about nothing. The same router, modem, computer, ISP and config.

Here my result:
http://www.dslreports.com/speedtest/5260111

My connection is 100/2 Mbps with QoS settings about maximum, speed settings 100352/2000 Kbps
vdanilchenko
DD-WRT Novice


Joined: 08 Oct 2016
Posts: 8

PostPosted: Sun Oct 09, 2016 1:03    Post subject: Reply with quote
With QoS, I got 10Mbits down and 10Mbits up, and on second test 10Mbits down and 0.3Mbits up, vs. Ookla showing 3,10 and 3,10 twice in a row.

Without QoS, I got 30,10 and 8,12 from DSLReports, and 2,12 and 2,12 both times from Ookla.

All the download values are vastly slower than my cable's capacity, though, and as you can see, they are jumping all over the place.
B@R
DD-WRT Guru


Joined: 16 Apr 2011
Posts: 599
Location: Israel

PostPosted: Sun Oct 09, 2016 1:11    Post subject: Reply with quote
Did you used LAN, or wifi?
I have the very close results for the months with the same router.
B@R
DD-WRT Guru


Joined: 16 Apr 2011
Posts: 599
Location: Israel

PostPosted: Sun Oct 09, 2016 1:15    Post subject: Reply with quote
It may be because WiFi, if you use it.
Are you sure, that QoS borders are in KILOBITS, because in the router there are kbps values.
vdanilchenko
DD-WRT Novice


Joined: 08 Oct 2016
Posts: 8

PostPosted: Sun Oct 09, 2016 1:52    Post subject: Reply with quote
I had used WiFi before, but I re-tested with LAN, and got the following results:

No QoS: 27,12 and 28.11 from DSLTest, and 26,12 and 26,12 from Ookla.

QoS (and my laptop at max priority): 29,10 and 30,10; and from Ookla: 31,10 and 26.10.

All the while I am monitoring the bandwidth usage in DD-WRT, and it stays within the expected range (30Mbits), i.e. about 6 times less than my cable capacity.

And yes, I set all the bandwidth limits in kilobits, i.e. my downlink is set to 160000, and my uplink is set to 11000.

My last test result:

http://www.dslreports.com/speedtest/5260552

Thanks for your help guys.
vdanilchenko
DD-WRT Novice


Joined: 08 Oct 2016
Posts: 8

PostPosted: Sun Oct 09, 2016 2:27    Post subject: Reply with quote
I just did an NVRAM reset(by doing 'erase nvram; reboot'), and ran the tests over Ethernet, without turning on the WiFi -- same outcome... 35Mbits/second download speed, rather than the 180Mbits I get when I connect directly to the cable modem.
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