The problem is definitely in the channel. 2 options: either it is too narrow or congested.
Because on another computer in the local network the problem is not observed — the error can be localized:
1. Configure Switch/Router home network. Just try to reset it. Maybe your MAC/IP was in the ban list for flooding.
2. Damaged cable from Switch/Router to your computer. Try to ring. Either a multimeter, or swap cables with another computer.
3. The network adapter on your computer. Either it is faulty, or configured incorrectly. Reset, change the MAC, put it in another slot on the motherboard, swap the adapters with another computer.
4. Congestion of the channel. Find special tools
and disconnect the demanding program\services.
5. The channel is blocked or restricted. Check your computer for viruses. Disable all firewalls, antiviruses, etc. to Read
6. The OS is faulty. You can try booting with a Live CD and check the connection quality there.
If all else fails — the error is not in you. Perhaps your ip+mac restricts provider.