Posted: Sat Oct 08, 2016 23:33 Post subject: TP-Link Archer C7 v2 -- highly inconsistent download speeds
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?
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.
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.