Connecting two Local Area Networks each with different ISPs together is rather straightforward and simple.
Client/LAN IP range: 192.168.1.3-50
Client/LAN IP range: 192.168.1.51-100
Configuring each Routers’ IP range for clients that will be connected to it is necessary to avoid conflicts, whether you are giving client computers static IP addresses or DHCP.
IP: Static or Obtain dynamically from Router
Subnet: LAN1 and LAN2 are the same, depending on how huge is the network
Gateway: Either of the two routers. For this example: 192.168.1.1 or 192.168.1.2
Workgroup: to your choosing
Test your connectivity by pinging other computers.
Test your LAN Speed.