Yay!
There’s one more thing to check before doing the happy dance: configure the router so it cannot assign the Ruida’s static IP to another device on the LAN through DHCP.
If the PC and the Ruida have a direct connection, without using a LAN, then that doesn’t apply, because there is no router. However, if it’s on a LAN, this detailed discussion covers the problem:
My Verizon router has a simple way to set the DHCP IP range, but other ISPs / routers make that impossible. Let us know if you run into trouble, as somebody around here may have roughly the same setup.