I often loose connection from my PC to the wireless router. Normally I restart my router and the communication starts again. But now some of my PC can’t connect. I can see the wireless point and the signal strengths in the PC, looking at the router is “very good”. I have used the "repair" and "diagnostic" function to get the connection working, but get the information – the IP address can not be renewed – what could be the problem and how can I solved it?

The router is a D-Link DI 624+ with stronger antenna. 3 of the switch port are connected and 3-4 PC are connected via wireless. The PC card is a D-Link Airplus Xtreme G DWL-G520

Download a free app called "Netstumbler" so you can find a good channel to use by using s/n ratio.

You can try "ipconfig /renew" from the cmd prompt.

Your wireless router can be going bad. Had that happen too, but interference is first to check.

Are you getting "media disconnected errors" . Occaisonally I get them and "net start "wireless zero configuration" from the cmd prompt fixes that.

Considering you have 3-4 or more computers accessing the DI-624 at the same time, it could be that your router may not be able to handle the congestion traffic.

Try to ping from each computer to the router (one at a time, while the others are not connected to the router) to find your latency (ms) times. Then do it again with all of them connected, and different times of day.

You also have to consider that even if PC's seem idle, they may be downloading Windows Updates, anti-virus updates, so on, and maybe at the same time.

As Keepit said above, Netstumbler is a good tool. You might also want to change the channel your router is on if your neighbors are on the same one, or close to it.

Another helpful wifi connection boost, and very easy to make in less than 15 min, is the windsurfer parabolic reflector-- for your router's antenna(s) or your pc/laptop external wifi adapter antenna. It does boost signal by even up to 6db or more.
Ez-12

Thanks for your feedback. I disconnected - connected the wireless connection in the trouble PC and I got the system to work. I also decide to install a D-Link DIR-655 router to get more power to support the wireless PC.