I have a ProBook HP laptop with 12.04 (PB-1), it connects to the WIFI and works fine. Now, I have just installed another ProBook (PB-2) with 14.04 (not 12.04), also connected to the WIFI, and sometimes this second computer loses or slows down dramatically its connectivity. The router is configure with DHCP, and, as I can see with ifconfig, they have different IP addresses (192.168.1.41 and 192.168.1.34). Eventually, other computers/mobile devices get connected to the network, but always with different numbers, so it doesn't seem to be a collision problem.
The laptop has a fresh installation, didn't change anything in its configuration.
I've checked that there's an interaction between both laptops. Most of the times, PB-2 can't access if PB-1 is connected (but once I could do a speed test of both connected at the same time, and yielded similar results). Verified with firefox and chrome. (Of course, PB-1 is not heavy-downloading anything, this lasts for a week, since I first installed 14.04.)
Edit:
00:19.0 Ethernet controller
[0200]: Intel Corporation 82579V Gigabit Network Connection
[8086:1503] (rev 04) Subsystem: Hewlett-Packard Company Device
[103c:1621] Kernel driver in use: e1000e -- 24:00.0 Network controller
[0280]: Broadcom Corporation BCM4313 802.11bgn Wireless Network Adapter
[14e4:4727] (rev 01) Subsystem: Hewlett-Packard Company Device
[103c:145c] Kernel driver in use: wl
The only difference is at the very end of the message: wl for the first ProBook (the one working fine), and bcma-pci-bridge for the second one (slow).
Edit:
The Broadcom Wireless Card indentified for both laptops is
[14e4:4727] (rev 01)
corresponding to this entry in the PCI.ID table:
PCI.ID 12.04 LTS 14.040 / 14.10 LTS
------------------------------------------------------------------------------------
14e4:4727 Special Case #3 Special Case #1
which reads as:
Special Case #1 - This device uses the driver combination bcma and brcmsmac. It shouldn't be necessary to install anything at all. Required firmware is installed by default in the package linux-firmware.
Wireless script result for PB-1.
Wireless script result for PB-2.
Wireless script result for PB-1 after removing the STA driver.
Edit:
HW configuration of both ProBooks:
7,7GiB memory
Intel Core i5-2410M CPU @ 2.30GHz x 4
Intel Sandybridge Mobile
64-bit
plenty of disk in PB-2, same HD in PB-1, but here there's only some 1GB left (sharing with Windows).