My dad has the same problem: can access internet

the first 10 minutes when the pc is turned on, then cannot access internet anymore. Exactly 10 minutes. I tried 9 min 58 sec, it's OK. 10 min 2 sec, it becomes bad. Reboot or turn on get another 10 min.

I spent two days, but never found out why. My mom's computer on the same router doesn't have this problem.