Frequently lose internet connection

First, some background: A few weeks ago, we believe we had a power surge come through the high-speed internet cable since we came home that evening (after some storms in the area) and everything that was connected to that setup wasn’t working. All other things that were just connected to a power supply were fine (printer, monitor, etc.) We’ve gotten a new cable modem (actually, 2 since the first one was defective), Dell replaced the motherboard and power supply (that 4 year warranty has paid off!!) and we got a new Vonage phone router (with wireless capability we didn’t have before). I’ve also replaced the CAT5e cables connecting the modem to router and router to computer. AND, gotten a new surge protector that also allows the coaxial cable to be protected as well. I know the modem and router work fine since my phone service is no longer having problems. So, this is a computer problem. The computer diagnostics say that the NIC is working properly. My husband downloaded a new driver for the NIC but this problem was happening before that. We’ll be online and then just lose the connection. Sometimes I can repair the internet connection and that will fix it for a short while. Sometimes, it can’t repair since it can’t renew the IP address. Usually, restarting the computer will get us connected, again, for a short while. I did talk with a Dell technician and he had me put the computer in safe mode with networking and it worked fine. It also worked fine in a selective startup mode (through msconfig). I was able to view several videos w/no problems – something I can’t do in my normal start-up mode. I’ve tried most of the things suggested in previous posts, but now don’t know where to turn – except to the Geek Squad. I should add that even tho’ the router now has a wireless capability, we don’t use it. I think I did make it a secure connection so neighbors can’t access. Thanks for your help!!