We have a Draytek Vigor 2800G router at one of our sites.
There are PCs connected to it all the time that have no issues connecting to the internet.
However, when laptop users come in to the office and plug in (note: not using wireless) to the router, there is an audible click and the internet connection switches off.
I have tried a new cable, but this has not had an effect.

Does anyone have any ideas what might be happening here?

• We currently have a Draytek Vigor 2820 router in place.
• The line is a shared line with the whole building, not just the office in which this router sits.
• The line is maintained by the landlord’s IT department.
• Nobody in the other offices in the building have internet problems.
• You only have 1 PC that is permanently connected to the router.
• The internet there works fine until laptop users are in the office.
• It makes no difference whether the laptop users use wireless or different cables.
• When laptop users connect to the internet through the router, there is an audible click from the router and the internet connection drops.
• The internet comes back after the router is switched off for 30 minutes and back on, and then works for everyone for a while until this happens again sporadically.
• We have swapped out the cable for a new one (to eliminate the cable).
• We have moved the cable between ports on the router (to eliminate the port on the router).
• We have tried 2, brand new Draytek Vigor 2820 routers there (to eliminate the router).

I had this issue when a customer plugged a cable from one LAN port to another LAN port.

It sounds to me asthough the network card in the laptop if broken and this is causing (possibly) some sort of loop.

If all else fails you could try to put a small cheap switch in between the laptop and the router.