Using two routers with one for internet access

Two routers are needed sometimes.  One common scenario is that a router’s internet connection (the WAN part) is out of service, so another router’s internet connection needs to be borrowed temporarily while maintaining the LAN of the original router. If there are any port forwardings, they need to be set up on the temporary router in this case.

A computer can connect to two routers (e.g. one with Ethernet cable and the other with WiFi).  Microsoft Windows can handle this seamlessly, but there is one problem – Windows may not use the internet connection that it has detected from a router.  This is because two routers create two default gateways, and the gateway with the lowest metric is used.  To use the internet connection from a router, one needs to make sure the gateway corresponding to it has the lowest metric.  Fortunately, there is a utility program for doing this – NirSoft’s NetRouteView. If the metric of the desired gateway cannot be lowered, one can increase the metric of the other default gateway to address this issue.