I have an old PC that hasn't been turned on for 4 months. Today I turned it on, linked an ethernet cable (the cable that I use every time) and the network started to behave weirdly. Firstly, I opened Steam and set CS:GO to download. It downloaded 1.6gb and while it was downloading it, I set another thing for a download so I can have two downloads at the same time on independent programs. Suddenly my CS:GO download stopped, the other program's download stopped as well. I tried to restart the downloads but had no luck. At first, I thought that my internet is down so I went on the local newspaper's site (www.time.mk) and it opened perfectly with the latest news. I then went to google and got an error that "Couldn't be found". I opened my CS 1.6 then and connected to a server successfully without any lag or something weirdly.

I connected via WiFi on my laptop and opened 192.168.1.1 (this couldn't be opened from my PC as it kept trying to open it but never did actually) and as far as I know, since it works via the WiFi, I believe that the Firewall isn't the problem.

I'm not experienced with networking and stuff but can you guide me and tell me what to check in order to fix this problem before getting a conclusion that it might be a hardware problem (this is currently my guess)?