Here are two issues:

  1. When you use static IP, the router may not detect them. You’d better use DHCP. What is your firmware version? Can you post a screenshot?

  2. When you want to “reach any of the devices in the LAN network”, do you mean that you want to reach them from your vpn server? Does your vpn server allow this? If yes you need to set up port-forward in your router as well.