Internet dropping out; desktop using bandwidth

[Dysfunctionalbanshee]

My connection goes out after awhile of me watching Netflix and talking on discord. My company says my modem is fine. When I troubleshoot it says there is connectivity issue to the modem. I have my wireless router plugged in through the modem and the desktop plugged into the router. They also told me something caused my computer to use up all of my bandwidth... I am not sure if I need to replace the router or what to do to fix this issue??? I had this router for three years now. Could it be both or how do I know?
None of my devices work after it disconnects. (ie; wireless or desktop)

 

[GhislainG]

Can you connect your PC directly to the modem? If it works fine, then the router probably is the issue.