Internet stops working after seconds

[BaaBaaFatSheep]

I recently switched modem and now Internet stops working after a few seconds (on old modem internet was working fine) of connecting to it through wireless. Wireless and wired internet works on multiple other devices but my pc. Which is using 4965AGN. I tried reinstalling wifi drivers in compatibility mode (no windows 8/10 drivers).

Wifi sometimes shows Unidentified Network.

Diagnosing issues tells me that One or more network protocols are missing on this computer,
Diagnosing the Wi-Fi under change adapter settings I get The default gateway is not available.

 

[Kiril_Petkov]

@BaaBaaFatSheep could you please be more specific what is modem model , OS on the problem PC, PC/laptop model/specs. If you are missing protocols you should check you Control Panel\Network and Internet\Network Connections select you network adapter -> Properties
tell us what protocols you have install there. Also your new modem is using IP4 or IP6?