Congratulations on making some progress. Strange that the antminer is not visible on your network.  I don't think that the router can modify the antminer's address, if you set it as a fixed address. There could be a faulty component - try swapping the Ethernet cable between the Antminer and your switch or router with another cable.  Try using another port on the switch or router that the Antminer connects to (had some instances that a port got 'zapped' by lightning induced transients).  Usually the switch or router has an indicator light for each port - can you see that the port recognizes that the cable from the Antminer is plugged-in?  If your router supports LAN IP assignment, you could 'pre-allocate' the same fixed IP address that you set up in the LAN gui to that antminer (you'll need to find the MAC address of that device, which sounds like a 'chicken and egg' situation, as the easiest way to find that is to check your router configuration... however you could also reconnect the PC directly to the antminer to find the MAC address).
Did you remember to re-configure your PC back to DHCP mode?
Did you set the WAN address on the Antminer?  (you don't need to change the LAN, only the WAN, this is confusing as the controller board used was probably meant to be a router, but as per all the guides and direct experience, the only part that you need to set is the WAN).
Are you certain that your router covers the IP address range that you set the antminer to?  (check your router configuration).  Is there a chance that there is another device already using the IP address that you set the antminer to?

What make/type of router are you using?
Can you post screen shots of your Anminer's configuration screens for the network settings?

I have followed this routine with plenty of S1's and S3's and it always worked fine for me.
Cheers