Can I change the WiFi card on Macbook Pro 17" (Early 2011)? I am having an issue with my very old Macbook Pro 17" which is the early 2011 model and would appreciate any advise to that end!

The wifi works only rarely and it just gets disconnected all of a sudden! Then, it becomes unable to find any network and I have to turn it off and on many times to bring it back which goes in a minute again!

So, my question is if it is possible to change the WiFi card for this model?

Thank you very much for your help already!
The short answer is Yes.

It's actually one card for both Airport/Bluetooth connectivity and the part numbers you can choose from are 661-5867 (Bluetooth 2.1) and 661-6510 (Bluetooth 4.0). These cards can be used in multiple MacBook Pro models, including all of the early 2011 models. 

Be careful not to make the mistake of getting the one suited for the Late 2011 17" model, as this is not the same - although the 13" and 15" Late 2011 models do use the same card as your MBP.