192.168.100.1 is an IP address from a private address space and could be used to address 254 IP addresses in a class C network. IP addresses from 192.168.100.2 to 192.168.100.254 are assigned to the devices in the network. Router uses 192.168.100.1 IP address to identify itself on a network and every device which needs to connect to the router will use 192.168.100.1 to find it.
192.168.100.1 IP address could be used by the following routers:
To access your router administrative UI go to your browser and type 192.168.100.1 into the address bar. Press Enter. If you don't see router login prompt then most probably your router is using another IP address to identify itself. Read our access default router page on how to find out a correct router IP.