[awtas]

This is what I have
Router Model Netgear R6300V2
Firmware Version DD-WRT v24-sp2 (11/20/14) std - build 25408
Kernel Version Linux 3.10.60 #3101 SMP Thu Nov 20 01:55:04 CET 2014 armv7l

There were no recent changes applied to the router config.

For the last couple of weeks I am experiencing inconsistent speeds using wireless, this applies to both 2.4 and 5 GHz (two different laptops).

Wired I get 150/10 speeds and speeds are steady (consistent) while using wireless my speeds are varying from 2 to 90 download.
Upload is as expected.

Any suggestions on how to troubleshoot the issue?

Does that mean that I need a new router? (my router is 15 months old)

Additional details:
2.4 GHz network is set up as N only, channel 7 (20 MHz)
5 GHz network is set up as mixed N/AC, Auto channel, (20+20 MHz).
I live in the apt building and channels (1,6,11) have about 5-6 networks on it, that's why I used channel 7.

Remaining settings are default.

Is it possible that my speeds are so inconsistent due to the interference with other networks? Is there any way to troubleshoot it?

[awtas]

Did additional troubleshooting. Hooked up my old
Router Model Netgear WNR2000v3
Firmware Version DD-WRT v24-sp2 (03/19/12) std - build 18777
and did not observe the same issue (speeds are still much lower than I would like it to be (down ~30 Mbps) but at least it looks that it is steady. I assume chances are high that my router is at fault.

Already tried reset, 30/30/30, haven't tried yet reinstalling either new ddwrt or back to stock. I also doubt that this is soft related issue, as it didn't exist up till two weeks ago.

Is there anything I can try to fix it? Also not sure if there's any way to eliminate the congestion in the area or other external interferences?
Would really hate looking for a new router.

[awtas]

bump
--
Is it worth to try restoring original FW or I just should get a new router?

[awtas]

Wanted to pass additional updates.
Had a visit from Comcast's tech team.
No luck. Checked wires and signal, all good.

After that I replaced modem SB6141 and router (R6300v1 with original FW).
Issue is still there.
I realized that issue started about the same time Comcast upgraded speeds.
Called Comcast again, same story, you need a technician back. I politely refused and asked to escalate it. Only download speeds are slow, upload is as expected.

Comcast promised to call back within 48 hours.
Will see what they say.
I suspected they messed something up while upgrading speeds in the area.

[MDA400]

If your wired speeds on your router are consistent to your internet speed tier, then unfortunately wireless is behaving as expected.

See if there is any neighboring access points interfering on your 2.4ghz and 5ghz interfaces using site survey under administration->wireless.

If so change the wireless channel to one with least interference. Also as always you could be at that range where the bandwidth fluctuates due to deteriorating signal through walls and such. This is the nature of the beast that is wireless so a powerful but minimally interfering router will give the best performance.

For example. In my bedroom here, im about 40 feet from my dual band router on 5ghz and i get a 40mbps link rate (not enough for my 105mbps from comcast), 20 feet i get ~216mbps, and next to it i get the full 433mbps that my LG G2 smartphone can do with wireless AC.

Wireless is a two way street. You could have better transmit signal (upload speeds) farther away but have lower receive signal (download speeds) and that can be due to the fact that routers have more powerful radios than phones or computers do.

[awtas]

Thank you MDA400.
I do understand that there are many factors however I cannot explain why the speeds are varying from 90 to 10 sometimes going to a complete crawl (1-2 Mbps) while location of my laptop remains the same.
Wireless signal is quite strong (-35 dBm) while there are other networks around, this wasn't an issue up till a few weeks ago where I believe at about the same time Comcast upgraded speeds from 105 to 150 Mbps for my tier.

[js1662]

Don't use channel 7 as it will overlap with users on channel 6 and 11. More overlapping means more interference from others. Choose a channel only among 1, 6 or 11 as they are non-overlapping channels. Pick one that has the weakest and less signal from others. After you have changed the channel to 1, 6 or 11, try the speed with the laptop say 10 feet away with line of sight from the router and see if the problem still exist. Since there is no problem with LAN connection, I don't think the problem is related to Comcast. Also check the Tx power of the router, sometimes it is better with a lower power than a higher power especially for a aged router.

[awtas]

Checked other networks with inssider and moved to channel 6, same issue.
Thought maybe Comcast upgrade introduced some changes with the upgrade that my router doesn't like. as with the same infrastructure I used to get ~70 Mbps while 150 Mbps wired, now my wired speed increased however wireless went down.

[js1662]

[MDA400]

Again if your wired speeds are consistent, then the problem lies within your wireless router or wireless device. Comcast can only give support down to the modem and nothing that comcast changes can affect your wireless throughput and not your wired.

[awtas]

Thanks everyone for responses.
I do understand that asking Comcast to escalate it is a long shot.
Same issue whether I'm 1 ft or 20 ft from the router.
I don't think that it's my laptop, as same issue is observed on a different laptop too.
So far tried:
ACK - changed from 2000 to 300 - no improvement
Changed TX from 71 to 50, 60, 65, 75, 80 - 65 and 71 gained best results (42 Mbps) but not sure if that was accidental, as with TX 71 I sometimes get 90 Mbps.
tried changing TX/RX antennas, channel width 2, 20+20, security on/off... even attempted to change country settings and this is where my router crapped out and had to do a reset, I gave up for the night.
basically shooting in the dark.

[MDA400]

At this point i would say try a newer build than the one you are using (link to them is in my sig).

Changing tx power doesnt do any good as your increasing noise along with signal. If there are alot of neighboring networks, dont use 20+20 on 2.4ghz. Security should be WPA2-AES only

[awtas]

Upgraded to build DD-WRT v24-sp2 (02/04/15) std - build 26138, no changes.
If Comcast calls back, will ask them if they can downgrade me back to 105 Mbps to see if issue still exist. Not sure how the speed change might be related to the issue Im facing but that's the only thing that changed.
I think next option will be a new (different manufacturer router).

[awtas]

Wanted to send an update. No call from Cmcast. Issue still there. Getting down ~130 on N 5GHz, and about 30 down on N 2.4 GHz tried with multiple devices. So I guess is the network interference and just have to live with that or upgrade my devices to 5 GHz cards.

[nolimitz]