If the VPN is (part of) this problem, disabling it after the connection problem has occurred might already be too late to recover. You might try running without the VPN for a while... Consider using Cloudflare DNS, 1.1.1.1, which claims to be less invasive, to get away from Google's spying. And also consider setting FF to use only Https-only mode connections to sites you visit, and enable Https DNS lookup, if you haven't already done those. 
 I've an Inspiron 3880 that frequently loses its internet connection, either via ethernet cable or Wi-Fi. I've two other computers and a LG TV connected to the same router that don't have any issues. The 3880 is running Windows 11 Pro and all updates are current, including drivers and BIOS. I'm using an Arris T45 gateway and a TP-link AC1750 router.  This is what happens:  When opening a browser (Edge or Firefox), the connection to the homepage will fail. Running network diagnostics from within the browser results in a request to reset the router. Resetting the router will typically correct the problem for a while. Switching between ethernet and Wi-Fi will sometimes allow the computer to connect without resetting the gateway, sometimes not.  If, upon starting the computer OneDrive cannot synchronize, running the network troubleshooter via Settings will result in Windows not being able to find a problem. Opening a browser when this happens results in the above scenario. Other computers on the same network (an Inspiron 3793 laptop or HP notebook) when this happens have no connectivity issues, leading me to conclude the 3880 is the problem.  I have tried every troubleshooting procedure I can find to try to correct the problem from removing and reinstalling the network adapter in Device Manager, using Network Reset, Command Prompt commands and to a clean install of Windows. All fixes work for a while but the issue keeps returning. This has been going on now for about 3 months.  As I stated before, it doesn't make a difference if the computer is connected via an ethernet cable or Wi-Fi. Can there be a hardware problem causing this behavior? 
Inspiron 3880 not staying connected to network