There are two Dell laptops on our home's wifi:
- Inspiron 1525
- Latitude E5420
These connect along with several other devices (iPad, phones) with which we have no trouble at all. The laptops are both running Ubuntu 12.04.
Sometimes the laptops both work fine; but occasionally - often after a good hour or more of simultaneous use - one or other laptop will suddenly experience a very slow wifi connection. If the working laptop's networking is disabled, the problematic laptop's speed bounces back. Re-enabling the networking kills the problematic laptop's connection again. This has happened with each laptop sometimes having the problem; usually the one nearest the router is most likely to be OK.
Here's some of the things I've ruled out:
- MAC and IP addresses are different (
sudo ifconfig). But then if they were conflicting, then the problem would surely not be intermittent!
- Power management is turned off for both wifi connections (
- Router and ISP have both changed while we've had this problem: we switched broadband providers from O2 to The Phone Coop, but the problem persisted; at the same time we went from a Speedtouch router (I think) to a Technicolor TG582n. So it's unlikely that's the problem.
- Link strength is OK; but then again, unless two completely different routers had link strengths varying in similar ways, then you'd expect that to be the case.
Testing for a possible bug in the wl drivers (suggested by @Braiam) below, the output is as follows. On laptop-1:
laptop-1% sudo lspci -nnk | grep -A8 -i network 02:00.0 Network controller : Broadcom Corporation BCM4313 802.11bgn Wireless Network Adapter [14e4:4727] (rev 01) Subsystem: Dell Inspiron M5010 / XPS 8300 [1028:0010] Kernel driver in use: wl Kernel modules: wl, bcma, brcmsmac 03:00.0 CardBus bridge : O2 Micro, Inc. Device [1217:8134] (rev 06) Subsystem: Dell Device [1028:049b] Kernel driver in use: yenta_cardbus Kernel modules: yenta_socket 09:00.0 FireWire (IEEE 1394) [0c00]: O2 Micro, Inc. 1394 OHCI Compliant Host Controller [1217:13f7] (rev 05)
laptop-2% sudo lspci -nnk | grep -A8 -i network 0b:00.0 Network controller : Intel Corporation PRO/Wireless 3945ABG [Golan] Network Connection [8086:4222] (rev 02) Subsystem: Intel Corporation Device [8086:1021] Kernel driver in use: iwl3945 Kernel modules: iwl3945
Anyone know what are the likely remaining causes of this problem; more importantly, how do I diagnose and test those causes?