We have an old Cisco 1800 in a test lab. The two network interface are configured as follows:
The default gateway for PCs on the 6.X network is 6.33 - that is how they can get to the 5.X network.
The default gateway for anyone on the 5.X network is 5.1 (another router with Internet access).
The router with Internet access (5.1) has a static route so it can pass traffic to 6.X from 5.x via 192.168.5.33 (interface on the Cisco 1800).
All systems on the 5.X network can get to Internet no problem because their gateway is 5.1 and it can either send traffic to Internet or back to Cisco for access to 6.x network.
PROBLEM - All systems on the 6.X network CANNOT get past the 5.X network when trying to reach Internet.
Question #1 - How can we tell the Cisco router that traffic coming from 6.X needs to get to the Internet via the router on 5.1?
Question #2 - Do we need tell the router on 5.1 (a Sophos UTM, not cisco) anything about the 6.X network that is not directly connected to it?