My onboard Intel 82566DM-2 now and then refused to make internet connection. The last few days it almost stopped al all. Sometimes after 10 restarts it worked again. So I installed a Realtek 8169 network adapter which worked the first time and then gave the same problem: no internet connection.
All other computers/laptops in the network have no connection problems at all. I switched cabled to no avail.
Anyone a suggestion where to look for a solution?