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linux_matt
Tux's lil' helper
Joined: 14 May 2012
Posts: 103
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 Posted: Sun Sep 27, 2015 3:02 pm Post subject: Wifi packet loss even at minimal distance from router |
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I am experiencing packet loss of up to 50% on wifi whereas wired connections work perfectly. This happens when a wifi client is right next to the router (less than 1 metre), at longer distances, and also happens at both 2.4GHz and 5 GHz frequencies and on different control channels. The network configuration is a British Telecom (BT) Home Hub 4 connected to the Internet and an ASUS RT-AC87U as a wireless access point. Wired connectivity between the WAP and the router is fine, ditto between the WAN connection and the ISP, there are no cabling issues or ISP issues. There are 2 laptops running Windows 7, one can only operate wirelessly as 2.4 GHZ, the other can operate at both 2.4GHz and 5 GHz. There is also a wired connection to a PC running Gentoo. Some statistics are below. Grateful for any suggestions as to why the wireless connections are so slow and unreliable? There are some possible sources of interference such as DECT phones but I have switched these off. Or maybe there is an instrument that could measure interference in the house?
At certain times it appears that the connections can work OK but for many hours there are these wireless connection issues.
Ping the BT router from a wired Gentoo PC
icmp_seq=1 ttl=64 time=0.781 ms
icmp_seq=2 ttl=64 time=0.695 ms
icmp_seq=3 ttl=64 time=0.699 ms
icmp_seq=4 ttl=64 time=0.722 ms
icmp_seq=5 ttl=64 time=0.701 ms
--- [IP address] statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 3996ms
rtt min/avg/max/mdev = 0.695/0.719/0.781/0.043 ms
Ping the BT router from a 5GHz wireless Windows laptop connection. Distance from router is 0.6m. Wireless signal strength is -33dbm
Packets: Sent = 5 Received = 4 lost = 1 <20% loss>
Round trip: Min = 6ms Max = 82ms Average = 50ms
Ping the BT router from a 2.4GHz wireless Windows laptop connection. Distance from router is 0.6m. Wireless signal strength is -27dbm
Packets: Sent =5 Received =2 lost =3 <60% loss>
Round trip: Min = 625ms Max =1121ms Average =873ms
Ping the ASUS router from a wired Windows laptop.
All statistics 0ms because connection is very fast/reliable
Ping the ASUS from a 2.4GHz wireless Windows connection. Distance from router is 0.6m. Wireless signal strength is -17dbm
Connection seems to be very unstable. Sometimes ping request times out. At other times ping acknowledges request for the ASUS router's IP address but reports that the destination address for a different IP address (router address incremented by 1) is unreachable |
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lexflex
Guru
Joined: 05 Mar 2006
Posts: 363
Location: the Netherlands
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| Posted: Sun Sep 27, 2015 6:17 pm Post subject: Re: Wifi packet loss even at minimal distance from router |
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Mmm, sounds nasty, particularly since it is both in 2.4 and 5, and in various channels. This *might* mean it is a router/ AP problem, and not interference.
Some ideas:
I had a similar problem with my (provider provided) access point next to my ( provider provided) digital DVB-c tv decoder.
Moving them more then 1.5 meter apart helped ( although it was highly unpractical). Maybe something to try / check.
| linux_matt wrote: | Grateful for any suggestions as to why the wireless connections are so slow and unreliable?
There are some possible sources of interference such as DECT phones but I have switched these off. |
Other know sources might be fire/smoke alarms in the 2.4 GHz band.
However, they shouldn't use the whole band, so if you tried switching channel this is unlikely.....
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Or maybe there is an instrument that could measure interference in the house?
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Again, there are some apps that measure free wifi channels. However, you tried multiple channels allready.
One more thing: The distance between AP and client is one thing, but is the AP standing freely ? Mayby ( for testing purposes) move the AP to the middle of the room , and test again. Materials or devices near the PA might cause trouble.
Good luck,
Alex. |
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lexflex
Guru
Joined: 05 Mar 2006
Posts: 363
Location: the Netherlands
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| Posted: Sun Sep 27, 2015 6:37 pm Post subject: Re: Wifi packet loss even at minimal distance from router |
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>> there are some apps that measure free wifi channels. However, you tried multiple channels allready.
One more note: The apps on your smartphone that measure free WiFi channels ONLY look at wifi. This means they usually do not detect other interference.
However, f.e. Bluetooth and ZigBee also work in the same band. So of you happen to have some ZigBee gateway or something like that, this might also be worth considering. |
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linux_matt
Tux's lil' helper
Joined: 14 May 2012
Posts: 103
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| Posted: Tue Sep 29, 2015 6:14 am Post subject: Re: Wifi packet loss even at minimal distance from router |
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| lexflex wrote: | >> there are some apps that measure free wifi channels. However, you tried multiple channels allready.
One more note: The apps on your smartphone that measure free WiFi channels ONLY look at wifi. This means they usually do not detect other interference.
However, f.e. Bluetooth and ZigBee also work in the same band. So of you happen to have some ZigBee gateway or something like that, this might also be worth considering. |
Many thanks for this, the WAP router is indeed near similar equipment (2 x DVB-T recorders) and it seems to help to move the router further away. |
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lexflex
Guru
Joined: 05 Mar 2006
Posts: 363
Location: the Netherlands
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| Posted: Tue Sep 29, 2015 8:01 am Post subject: Re: Wifi packet loss even at minimal distance from router |
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| linux_matt wrote: |
Many thanks for this, the WAP router is indeed near similar equipment (2 x DVB-T recorders) and it seems to help to move the router further away. |
Ok, good that it helped !
It is a strange problem (also in my case) since the dvb-stuff (both c and t) operates at very different frequencies and shouldn't be broadcasting or anything.
So probably just bad shielding, bad grounding, and/or cheap electronics design 
Alex. |
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khayyam
Watchman
Joined: 07 Jun 2012
Posts: 6227
Location: Room 101
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| Posted: Tue Sep 29, 2015 11:00 am Post subject: |
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linux_matt, leflex, et al ...
the following is probably worth keeping in mind (source) ...
| Craig Mathias wrote: | [...] wireless introduces two additional variables over which one doing the testing has no control:
- First of course, in the nature of radio propagation itself. This is a fundamental, physical (as in physics), unpredictable, statistical, non-linear phenomenon that's essential to the universe itself. Good luck dealing with that one beyond long run times, multiple runs, and using turntables where possible to factor out antenna orientation (although, in the case of beamforming, such obviously isn't a good idea). But physics is physics and care is thus required in doing comparative testing
- Second is the nature of the 802.11 protocols themselves. Every product vendor, or at least WLAN chip vendor, has their own unique take on how best to use these, and drivers additionally allow a degree of variability in a number of key parameters. Add in settings like transmit power, and you have the makings of a multi-week exercise that might still not yield definitive results. But we can get close or at least derive an inference or two in most cases.
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In terms of measurement you might look at net-misc/iperf, and zapwireless ... ping isn't really suitable.
Location: I've found that mounting the AP on the intersection between the ceiling and wall, facing downward (with antenna pointing toward the floor, or at an '/ \' angle) will improve reception and reduce interference.
Channels: airmon-ng (net-wireless/aircrack-ng) can be used to look at AP's within range, and will show the channels, and signal strength ... you should be looking for some separation (ie, non-adjacent channels) between the strongest signals, and whatever channel you choose.
2.4GHz and 5GHz: you might try disabling one or other on the AP, mixed networks are generally less stable in my experience.
HTH & best ... khay |
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