Nighthawk R760P VPN Connects, but I can't connect to local PCs

You have run head on into an IP address conflict.  The 192.168.1.x range of IP addresses is the most common in use on local networks.  When the local network your are tunneling into has locally assigned IP addresses that are the same as assigned addresses at the remote location you have a conflict.  When that happens, the 192.168.254.2 is often the default address assigned to the remote device.

Many times at the remote location you are connecting from, you have internet access yet you do not have authority to change the 192.168.1.1 IP address range assigned by the DHCP server.

The best solution is to set up your home DHCP server to assign IP addresses from a range that is not likely to conflict with whatever you run into at the remote location.

Set up your home LAN setting pool to assign addresses from the 192.168.4.x range as an example.  If you have devices on your home network with fixed IP addresses, you will have to move them to the 192.168.4.x pool also.

Buried somewhere on the OpenVPN website is a paragraph or two recommending methods for setting up a local network to avoid IP address conflicts between the two networks you are tunneling between.  I use Open VPN to connect back to my home from a lot of different remote locations.  My home router and all network devices are assigned IP addresses that start with 10.55.x.x.