@Halestormm 

Hi, In order to use VPN you need to make sure that some settings are configured properly:

1. Does your IPS provide you PUBLIC IP addess? That is crucial, without that whole VPN won't work. Most of ISPs are providing PRIVATE IPs and you have to ask the to give you public one (in most cases it's additionally paid service). If you are not sur, you can always ask your ISP.
2. If I understood correctly what you typed, you have ISPs device which gets IP address from ISP, and your TP-Link router is connected to that device and gets some internal [192.168.X.X] IP address. That would indicate you have double NAT (one on ISP device, second one on your TP-Link). In that case you need to make sure that proper PORTS are forwarded on ISP's device to your TP-Link router. [Or get ISP's device set into Bridge Mode]
3. Once both abouve are fulfilled, you do indeed have to manually edit OpenVPN config file and put there your PUBLIC IP address. The easiest way to know it is to visit some "What's My IP" web page and check what IP is showed there.

If everything is configured properly (server, config file, ports) as well as ther is Public IP assigned, then it shall work.

Sometimes the Firewall on client's PC may also impact the VPN connecton so it's worth check that as well.

Best Regards