Potential problem RT-AC68U (originally TM-AC1900) and WiFi driver 6.37.14.126

[sirwifi]

Call me confused! Here's what happens with WMM APSD = DISABLED (on LTS v26):

[  3]  0.0- 1.0 sec  12.6 MBytes   106 Mbits/sec   0.268 ms 1633/10648 (15%)
[  3]  1.0- 2.0 sec  13.9 MBytes   116 Mbits/sec   0.020 ms 2572/12456 (21%)
[  3]  2.0- 3.0 sec  12.8 MBytes   108 Mbits/sec   0.302 ms 4607/13772 (33%)
[  3]  3.0- 4.0 sec  13.6 MBytes   114 Mbits/sec   0.019 ms 2545/12235 (21%)
[  3]  4.0- 5.0 sec  13.5 MBytes   113 Mbits/sec   0.025 ms 2908/12535 (23%)
[  3]  5.0- 6.0 sec  14.2 MBytes   119 Mbits/sec   0.020 ms 3267/13382 (24%)
[  3]  6.0- 7.0 sec  13.7 MBytes   115 Mbits/sec   0.010 ms 2383/12161 (20%)
[  3]  7.0- 8.0 sec  13.3 MBytes   111 Mbits/sec   0.011 ms 4029/13510 (30%)
[  3]  8.0- 9.0 sec  13.7 MBytes   115 Mbits/sec   0.031 ms 2913/12681 (23%)
[  3]  9.0-10.0 sec  13.5 MBytes   113 Mbits/sec   0.078 ms 2914/12548 (23%)
[  3]  0.0-10.3 sec   137 MBytes   112 Mbits/sec   2.251 ms 30563/128112 (24%)

One of the better runs:

[  4]  0.0- 1.0 sec  17.4 MBytes   146 Mbits/sec   0.035 ms    0/12444 (0%)
[  4]  1.0- 2.0 sec  17.9 MBytes   150 Mbits/sec   0.024 ms    0/12788 (0%)
[  4]  2.0- 3.0 sec  16.8 MBytes   141 Mbits/sec   0.028 ms    0/11986 (0%)
[  4]  3.0- 4.0 sec  17.4 MBytes   146 Mbits/sec   0.484 ms  319/12718 (2.5%)
[  4]  4.0- 5.0 sec  17.3 MBytes   145 Mbits/sec   0.022 ms  628/12981 (4.8%)
[  4]  5.0- 6.0 sec  18.1 MBytes   152 Mbits/sec   0.025 ms    0/12916 (0%)
[  4]  6.0- 7.0 sec  16.1 MBytes   135 Mbits/sec   0.024 ms 1366/12859 (11%)
[  4]  7.0- 8.0 sec  18.4 MBytes   154 Mbits/sec   0.026 ms    0/13108 (0%)
[  4]  8.0- 9.0 sec  18.9 MBytes   159 Mbits/sec   0.027 ms    0/13510 (0%)
[  4]  9.0-10.0 sec  18.0 MBytes   151 Mbits/sec   0.028 ms    0/12842 (0%)
[  4]  0.0-10.0 sec   176 MBytes   148 Mbits/sec   0.040 ms 2312/128205 (1.8%)

I guess I know which way I want it. ENABLED that is.

 

[john9527]

One scenario (or SWAG - Silly Wild butt Guess)....on the older driver APSD couldn't be negotiated, so was never used. On the newer driver, the negotiation was successful, but the results weren't good.

 

[john9527]

WOW....is it repeatable?

 

[sirwifi]

Btw, are these temps normal or should I be worried about? The router is in open space, plenty of air around it. Not overclocking or anything crazy, running in AP mode, so no services either.

2.4 GHz: 50°C - 5 GHz: 53°C - CPU: 81°C

 

[sirwifi]

WOW....is it repeatable?

Some runs show minor packet loss, other runs major loss. But ENABLING it goes back to normal runs.

Quite possible my hardware is from some "special" batch, it's 3+ yrs old. Or if the temps above are not right then maybe it's not getting enough cooling so it throttles? I could see different drivers/firmware making it run hotter, though I only looked at the temps now on v26, not on v27 or 380.68

 

[sirwifi]

One scenario (or SWAG - Silly Wild butt Guess)....on the older driver APSD couldn't be negotiated, so was never used. On the newer driver, the negotiation was successful, but the results weren't good.

Maybe it's the other way around WMM APSD = Enabled is actually broken in the latest driver, it doesn't do anything (at least on my hardware)?

 

[john9527]

Maybe it's the other way around WMM APSD = Enabled is actually broken in the latest driver, it doesn't do anything (at least on my hardware)?

Could be.....but it appears to do something. I just enabled it on V27 (I usually run disabled), and now I get sporadic packet loss, but nothing like what you see. With it disabled, always 0 loss. Go figure

 

[strangeluck]

Some runs show minor packet loss, other runs major loss. But ENABLING it goes back to normal runs.

Quite possible my hardware is from some "special" batch, it's 3+ yrs old. Or if the temps above are not right then maybe it's not getting enough cooling so it throttles? I could see different drivers/firmware making it run hotter, though I only looked at the temps now on v26, not on v27 or 380.68

Your temps are roughly in line with mine, I'm at 48 and 50 Celsius for 2.4 and 5 ghz respectively. I have had this model since available, which is roughly 3 years (I actually signed up in advance on the website and received mine free of charge during the initial promotion).

 

[sirwifi]

Could be.....but it appears to do something. I just enabled it on V27 (I usually run disabled), and now I get sporadic packet loss, but nothing like what you see. With it disabled, always 0 loss. Go figure

Very confidence inspiring. We seem to be all over the place.

 

[strangeluck]

Could be.....but it appears to do something. I just enabled it on V27 (I usually run disabled), and now I get sporadic packet loss, but nothing like what you see. With it disabled, always 0 loss. Go figure

I just ran a series of tests in the same location I received occasional packet loss (though always less then 1%) with WMM APSD disabled and now cannot observe any packet loss after half a dozen tests.

[  5]   0.00-1.00   sec  6.13 MBytes  51.4 Mbits/sec  1.025 ms  0/785 (0%)
[  5]   1.00-2.00   sec  7.12 MBytes  59.8 Mbits/sec  1.109 ms  0/912 (0%)
[  5]   2.00-3.00   sec  5.91 MBytes  49.5 Mbits/sec  1.170 ms  0/756 (0%)
[  5]   3.00-4.00   sec  7.46 MBytes  62.6 Mbits/sec  1.255 ms  0/955 (0%)
[  5]   4.00-5.00   sec  7.42 MBytes  62.3 Mbits/sec  1.057 ms  0/950 (0%)
[  5]   5.00-6.00   sec  7.46 MBytes  62.5 Mbits/sec  1.201 ms  0/955 (0%)
[  5]   6.00-7.00   sec  7.41 MBytes  62.2 Mbits/sec  1.390 ms  0/949 (0%)
[  5]   7.00-8.00   sec  7.34 MBytes  61.5 Mbits/sec  1.720 ms  0/940 (0%)
[  5]   8.00-9.00   sec  7.39 MBytes  62.0 Mbits/sec  1.276 ms  0/946 (0%)
[  5]   9.00-10.00  sec  7.41 MBytes  62.1 Mbits/sec  1.401 ms  0/948 (0%)
[  5]  10.00-10.06  sec   392 KBytes  58.1 Mbits/sec  1.134 ms  0/49 (0%)

Edit: Ran another series of tests two floors up and I get more throughput and still 0% packet loss with WMM APSD disabled. I will definitely be leaving this option disabled. Great find!

 

[sirwifi]

Here's what the connections look like on my 2.4 band (from System Log > Wireless Log):

Stations  (flags: P=Powersave Mode, S=Short GI, T=STBC, A=Associated, U=Auth, G=Guest)
------------------------------------------------------------------------------------------
MAC                       RSSI    Rx/Tx Rate   Connected   Flags
B4:CE:F6                  -42dBm      24/1 Mbps    0:29:02  PS AU
64:BC:0C                  -68dBm       1/1 Mbps    0:29:08  PSTAU
3C:15:C2                  -35dBm   216/216 Mbps    0:29:11   STAU
AC:CF:85                  -43dBm    24/144 Mbps    0:29:12  PS AU
40:78:6A                  -57dBm       1/1 Mbps    0:29:13  PSTAU
44:65:0D                  -58dBm   144/144 Mbps    0:29:13   STAU
AC:22:0B                  -47dBm       6/1 Mbps    0:29:13  PSTAU

Powersave Mode seems to be active on most devices. Do I want to ask about T=STBC?

 

[sirwifi]

After all these years wireless is still disappointing, lots of troubleshooting all the time. I'm still a firm believer in wires and use them whenever I can.

 

[strangeluck]

After all these years wireless is still disappointing, lots of troubleshooting all the time. I'm still a firm believer in wires and use them whenever I can.

Maybe post a screenshot of your wireless professional settings (assuming you modified them from default)? I am in agreement with you that wired is better, but that doesn't solve your present issues. We have a couple T-Mobile phones in this house and none of them experience wifi calling issues and I cannot reproduce anywhere near your levels of packet loss. With WMM APSD disabled I cannot seem to achieve any packet loss at all (though I only have this one laptop to test on).

 

[sirwifi]

Edit: Ran another series of tests two floors up and I get more throughput and still 0% packet loss with WMM APSD disabled. I will definitely be leaving this option disabled. Great find!

Just remember to enable it if you run into any issues with phones, e.g. more battery use. It's supposed to help them go into power save mode (I guess doze on Android and still keep wifi on in a low power mode so that wifi calling works?)

I seem to get much better results with it on. Maybe if it's disabled the AP tries to talk to the slower devices all the time causing the faster ones to start losing packets? But if the slow devices are sleeping, the faster ones can then use all the bandwidth?

 

[sirwifi]

@strangeluck This is all I changed on the Professional tab (from defaults):

Short preamble
Enable Reduce USB 3 interference (even though I don't have any USB devices attached to the router)

Short/Long preamble doesn't seem to make a difference, maybe somewhat less bandwidth with Long but within margin of error. Doesn't seem to affect packet loss in any way.

 

[strangeluck]

Here are my settings just for comparison (not that I expect it to be much help).

Edit: Also; channel 1, 20mhz, wireless mode Auto.

 

[sirwifi]

Mine on LTS v26:

I see you changed DTIM and beacon intervals, or are those defaults on 380.68?

 

[strangeluck]

Mine on LTS v26:
I see you changed DTIM and beacon intervals, or are those defaults on 380.68?

No, I modified those values. I seem to recall reading somewhere once that highter DTIM intervals can negatively affect VOIP (though I have no evidence to back such a claim up, and yes, I know how DTIM works before someone tries to explain it to me). I have been rolling with these values for a long time without issue and tend to just repeat them which each firmware version. I also like to have a lower beacon interval for 5ghz (100) in the theory it will cause devices that are 5ghz capable to discover and connect to that band first (again, anecdotal, I am no expert).

 

[jrmwvu04]

I never use 2.4GHz, but I was intrigued so I ran some tests on the 1900P with the new driver (v27). The client is at a most extreme end of the house, iperf 3.1.3

2.4GHz, 200 mW

[ ID] Interval           Transfer     Bandwidth       Jitter    Lost/Total Datagrams
[  4]   0.00-10.00  sec  1.25 MBytes  1.05 Mbits/sec  3.481 ms  4/158 (2.5%)

2.4GHz, 100 mW

[ ID] Interval           Transfer     Bandwidth       Jitter    Lost/Total Datagrams
[  4]   0.00-10.01  sec  1.25 MBytes  1.05 Mbits/sec  51.814 ms  7/157 (4.5%)

5GHz, 200mW

[ ID] Interval           Transfer     Bandwidth       Jitter    Lost/Total Datagrams
[  4]   0.00-10.00  sec  1.25 MBytes  1.05 Mbits/sec  0.642 ms  0/159 (0%)

If I get a chance, I'll try it on the older equipment.

 

[rtn66uftw]

Btw, are these temps normal or should I be worried about? The router is in open space, plenty of air around it. Not overclocking or anything crazy, running in AP mode, so no services either.

2.4 GHz: 50°C - 5 GHz: 53°C - CPU: 81°C

It's fine. Mine has been running at this temperature for the last 3 years