It is possible to change the wifi card. My connection seems unstable and when i play games, d2r for example. I get connection interrupted.
Is there anything i can do before changing parts?

It's much more likely that it is your modem and/or router. I'm sure whichever laptop you have has a card that can be replaced, but that is the last thing I would try. I go through Spectrum's modems every 3 or 4 years, and have had 2 different mesh router systems in the past 3.

I recommend getting a USB dongle wifi adapter if you think its the PC, Keep the packaging in really good shape so you can test with it, if you get the same results you can take it back and upgrade your router.