I have seen a number of posts here and on numerous other web forums regarding linksys WLAN issues and they often didnt contain solutions to the observed problems so I thought I would put this post out there to document what I experienced and the solution that has solved my problems. Originally I had a good working wireless b network running with BEFW11S4 and a WMP11 PCMCIA card in my laptop and had 2xPCs on ethernet. Then I decided to re-arrange and switch to wireless g. I bought a WAG54Gv2 to handle the router/ADSL modem/ wireless side and ended up with two different wireless PCI cards WMP54Gv2 and WMP54Gv4 for the PCs, the laptops were now going on ethernet to the router. After setting up the network initially I found that the PCs would connect to the network and access the internet for browsing but downloading files from the net to the wireless machines rarely worked satisfactorily. The file transfer would start and hang almost immediately. The wireless machines also would not transfer files from the laptops on the ethernet side of the router. The PC with the v4 wirless card would also regularly fail to find the other machines on the network when browsing with windows explorer (XP Home Edition SP2, with all hotfixes) sometimes it would see the other machines briefly sometimes it would report that " The Specified network name is no longer valid " Gaming and internet browsing across this entire network worked fine. I tried various combinations of firmware and driver updates, disabling WEP and DHCP, fragmentation thresholds, channels and beacon intervals - plus all software firewalls were disabled. Today I finally found some settings that make a difference. I upgraded my router to WAG54Gv2 (australian edition) to 1.01.13 firmware (obtained from a link on australian whirlpool broadband forum) and I discovered that the two wireless PCI cards perform quite differently on different wireless channels. I can set channels which will make the v4 card not transfer files while the v2 card transfers files just fine and vice versa. Thankfully I also found a channel (9) that allows both the WMPG54v2 and WMP54Gv4 to both have a good signal strenth and both transfer files quickly and that is with WEP enabled and firewalls (zonealarm) active. Setups are as follows: WAG54Gv2 Router: Fragmentation threshold 2304 RTS threshold 2304 Beacon interval at 50 and DTM interval at 1 wireless G only Channel 9 64 bit WEP Authentication auto Control TX Rate Auto Logging disabled UPnP disabled WPM54Gv4 wireless PCI card Driver: v 126.96.36.199 rt2500.sys driver dated 21/04/2005 Frag Threshold 2347 RTS Threshold 2347 OS = XP Home SP2 WMP54Gv2 wireless PCI card Driver: bcmwl5.sys dated 17/07/2003 Frag Threshold 2346 RTS Threshold 2347 OS=XP Home SP2 Ethernet laptops are running XP Home SP2 and XP Pro SP2 Internet connection is ADSL 1.5Mb/256Kb Pings are 1ms wireless to ethernet and 2ms wireless to wireless Internet Download speeds: Wireless download from net at 155Kb/sec minimum for a 30Mb file with signal strength remaining at Excellent and link at 54mb/sec The same file downloaded to one of the ethernet machines downloaded at 149Kb/sec. ? A 272,391KB File transfer from the Ethernet laptop to the v4 PC took 2min 57 Sec. I can finally say I am happy with the network as it stands. The only reason I was messing around with it today is because I was setting up an interim connectivity solution so I could return the router and the v4 card and buy some alternative equipment. Touch wood, it looks like I might not have to. Hope this helps some of you.