0Resolved: Wireless video streaming problem

I have a very strange issue which is caus­ing prob­lems play­ing videos over a wireless‑n net­work.  Play­ing the videos causes the net­work to drop out after a short peri­od.  Some­times this only lasts for 2–3 seconds, which just causes a video stut­ter.  Oth­er times the drop out is more per­man­ent and takes nearly a minute to recov­er, unless the wire­less radio is switched off and back on, whereupon recon­nec­tion occurs.

Run­ning a con­tinu­ous ping dur­ing this res­ults in timeouts when the con­nec­tion drops.  The con­nec­tion is more likely to recov­er with­in 2–3 seconds if the video is paused as soon as the prob­lem occurs.  Now the strange part.  If I sim­ul­tan­eously copy a large file over the wire­less at the same time as play­ing the video then play­back is fine and no drop outs occur! This is affect­ing a wire­less con­nec­tion between a Draytek Vigor2820Vn and 2 dif­fer­ent laptops with Intel 5×00 wire­less cards.  Both laptops are run­ning Win­dows 7 x64.  I have also tried with an Intel 6300 Wire­less card.

I have so far tested and estab­lished the fol­low­ing facts (note: all speeds are giv­en in bits not bytes)…

1. The dir­ec­tion of the file trans­fer does­n’t mat­ter, it can be to the cli­ent or from the cli­ent (e.g. from A to C or from C to A).  It can also be ini­ti­ated by the cli­ent, or by the oth­er end of the trans­fer (i.e. ini­ti­ated by C).
2. The file trans­fer can be to a dif­fer­ent com­puter from the source of the video, or the same, it always has the same “pro­tect­ive” effect. (i.e. file is stream­ing from C to A, file copy is from B to A)
3. Play­ing just 1 video with a bitrate of 2Mbps does­n’t seem to exhib­it the issue? 2 Videos with a total of 4Mbps do suf­fer.  Videos up to and includ­ing 13Mbps all exhib­it the same issue.  High­er rates haven’t been tested but I expect them to have the same problem.
4. There are no oth­er nearby wire­less net­works effect­ing net­work per­form­ance, and file trans­fers work reli­ably at approx 70Mbps so the con­nec­tion is not band­width limited.
5. Increas­ing the buf­fer in WMP to 30 seconds has no bene­fit.  Fur­ther­more the jud­ders in video play­back still occur at the same time as the ping timeouts so the buf­fer does­n’t even seem to be working?
6. The router firm­ware is up-to-date, and it has had the wire­less board replaced without resolv­ing the prob­lem.  The issue also occurred with older firmware.
7. The drivers for the wire­less cards are up to date.  The issue also occurred the same with older drivers.
8. When the con­nec­tion cuts off it cuts off ALL wire­less cli­ents, even those not involved in the stream­ing so the issue *seems* likely to be at the router end of the con­nec­tion, not the cli­ent end? (i.e. when stream­ing from C to A, B is also cut off temporarily)
9. A web-down­load at ~300k/sec (2.4Mbps) does­n’t offer the same pro­tect­ive effect as the ~70Mbps file transfer.
10. The issue occurs even if the cli­ent (a laptop) is on bat­tery or plugged in.  So it seems unlikely to be power-man­age­ment related?
11. Dis­abled IPv6 without any benefit
12. Tried stream­ing video from both Win­dows 2003 (serv­er C) and Win­dows 7 (desktop D) hosts without change, so prob­lem isn’t related to SMB 2.0
13. Tried play­back with a vari­ety of play­ers includ­ing Media Cen­ter 7, Win­dows Media Play­er 12 x64, Win­dows Media Play­er 12 x86, MPC-HC x64 and VLC — all exhib­it the problem
14. Upgrad­ing to an Intel 6300 wire­less card makes no difference
15. The dis­tance from router makes no difference
16. The prob­lem hap­pens faster the more intense the traffic
17. The prob­lem hap­pens sig­ni­fic­antly less with a short­er wire­less key

My best the­ory is that the router has an obscure issue where it is redu­cing wire­less speed when it detects that the con­nec­tion is under low usage, but this low speed state isn’t suf­fi­cient for the peaks of required band­width in vari­able bit rate video streams and goes into some kind of error state which is only relieved when the video play­back is hal­ted.  Copy­ing a file is suf­fi­ciently intens­ive to pre­vent this state being entered, but a web-down­load isn’t.

Next I’d like to try one of the laptops with Win­dows XP as the OS instead of Win7, altho I don’t expect this to help.  Then I’d like to try a dif­fer­ent router / wireless‑n WAP which if my the­ory is cor­rect will cure the prob­lem.  Sadly I don’t have a source of a wireless‑n WAP or router at the moment.

If any­one has any oth­er ideas for things to try/test, or has a sim­il­ar prob­lem please get in touch!

Update 1 (5/Jan-2011)

I’m not the only per­son exper­i­en­cing this. Googling shows up a range of oth­er people who have had sim­il­ar issues but as yet no solu­tions.  List of links below…

Update 2 (23-March-2011)

I’ve updated vari­ous parts of the post, and added a series of links below.

I’m at a point now where I need to test my laptop with a dif­fer­ent Wireless‑N net­work.  If it works then I think I can con­clude there is a prob­lem with my router.  If it does­n’t work then there is some­thing wrong with either Intel wire­less cards, or with Dell Stu­dio laptops!

https://www.sevenforums.com/network-sharing/110061-windows-7-wireless-connections-drop-out.html — Sound sim­il­ar, but not quite the same.  My adaptor still sees wire­less net­works as far as I can tell

https://forums.whirlpool.net.au/archive/1300843 — Some people say­ing its Intel cards, but oth­ers say­ing chan­ging card did­n’t help.  Noth­ing conclusive.

https://forums.lenovo.com/t5/W‑Series-ThinkPad-Laptops/INTEL-5100–5300-Network-Dropouts-Disconnects/m‑p/97708 — Anoth­er spec­u­lat­ing about Intel drivers, but still with an unre­solved issue, so not very helpful

https://forums.smallnetbuilder.com/showthread.php?t=1997&page=3 — Sim­il­ar sound­ing prob­lem with a Belkin router.  Prob­lem resolved by repla­cing router.

Update 3 (30-May-2011)

I’ve tested the laptop con­nec­ted to 2 more wireless‑n net­works.  It works without any issue.  In con­clu­sion there is either a fault with the draytek or there is an incom­pat­ib­il­ity.  Hav­ing already sent the draytek back once before I am rather dis­ap­poin­ted that draytek failed to resolve the issue.

If you’re think­ing of get­ting a Draytek, con­sider an altern­at­ive.  I can recom­mend the Net­gear DGND3700