The laptop network port is loose. In order to connect to the Internet you have to wiggle the cable inside the network port. The light on the network port starts blinking only if you find the right position for the cable.
1. Bad network cable.
2. Damaged network port.
Possible troubleshooting steps and repair solution:
First of all, test connection with another network cable. It’s very likely that you have a damaged network cable. Replace the cable if needed.
Take a look inside the network port. Make sure there are no damaged pins inside the network port. It’s possible that one of the pins is bent and the connection to the network fails because of that. In some cases, you can straighten the bent pin with a thin rigid object.
It’s possible that the network port is broken and it loses contact with the motherboard when moved. In this case, it is necessary to replace the broken port with a new one. Unfortunately, this is not an easy repair. In most laptops, the network port is soldered directly to the motherboard.
You can work around this problem without replacing the damaged port. Simply buy a PCMCIA Network card. Plug this card into the available PC slot on your laptop and get a network port instead.