There are two different ways that hardware can affect your internet connection. Any time you install a new piece of hardware it has the potential of causing negative affects on a PC. If a computer looses it's connection to the internet following an install it could be a sign that the new part is either taking too much power or is causing conflicts in the system. Have the new hardware removed from the computer and retest your connection.
If you have installed any miscellaneous network hardware, such as IP cameras, storage devices, printers, etc, remove these prior to further connection testing. Once testing is complete and connection has been restored, reconnect these devices. If the connection drops out again, there is a good indications that the source of the connection issues are being caused by one of these network peripherals.
There is also a handful of network hardware that is found in every household connecting to the internet. Most simple home networks will be comprised of computer(s) connecting to a router/highspeed modem using a 10/100 Ethernet card. Depending on the ISP the router and modem may be separate, if this is your case, simply combine the two in the following steps unless otherwise instructed. Start by verifying that all devices are powered on indicator lights are functioning. Next, check any cables, both power and network, to ensure they are securely attached to the appropriate devices. If they have become disconnected then assure they are reconnected to the appropriate port. Routers are fairly simple to reconnect to if a network(ethernet) cable has come loose. Most home routers/broadband modems have 5 ports one being the incoming connection. Any of the ports besides the incoming connection is appropriate to connect to a PC. For networks with the modem and router separate, the incoming connection of the router should connect to the modem. If your computer(s) connects wirelessly this step should be skipped with the exception of the power cables and modem connection. Once you have verified the cables and your connection is still not working, move on to rebooting all major network hardware. Turn off the power to your router and computer(s), wait a few minutes and then return power to the devices. Once power is returned, allow the router and computer(s) to completely finish booting before attempting to verify the connection. If the connection is still not working check the router for any flashing or solid red lights. If one is visible verify it with your routers user manual. This will instruct you if your router has bit the dust.