I have a 35mbps network connection and in all other devices (laptops and mobiles) is working fine but only in this laptop no , on all devices the speed is around 30mbps but on this laptop its like 0.3 - 3 mbps why is this happening , what can I check ? Could there be other problem but wireless card ?
This happens more often than you think. A quick search of these forums will find many people with the same issue.
Things to try:
Change the type of WiFi ... if you are set to a/b/g, then try n or the other way ... you can find this in your adapter properties via the device manager.
Update/Reinstall drivers ... software corruption happens.
Remove software that might interfere ... stuff like "Lan Boosters" generally don't work like advertised. People have also reported issues with antivirus software that was not properly uninstalled.
Harder things to fix ... broken or disconnected antenna. Faulty network card ... best to try a USB adapter and see if that helps (especially if you have a spare around).
Go to your windows network connection properties and tell us the link rate and signal strength. Also tell us your model network adapter. I've seen people plug these in using USB 1 ports which is limited to 1.5Mbps and had a lot of overhead.
Where this information is located is dependent upon your windows version.