Where do you think I should start to troubleshoot if one out of 5 times I boot my system, the internet is not detected?

[kitnoman]

So my brother's pc is acting up. It's not major, but I would like to fix it before it get's worst(just in case). Basically, when the pc is turned on, there are times when it would say no internet and won't detect it. He would have to unplug the rj45 from the back of the computer and plug it back in before it would be detected.

[Hinjima]

1 minute ago, kitnoman said:

So my brother's pc is acting up. It's not major, but I would like to fix it before it get's worst(just in case). Basically, when the pc is turned on, there are times when it would say no internet and won't detect it. He would have to unplug the rj45 from the back of the computer and plug it back in before it would be detected.

Maybe something is up with the motherboard.  Reinstall network drivers. Change internet cable.
Worst case scenario: Get a cheap network card to see if that fixes the issue, if so the motherboard might be funky.