Murus internet sharing not working
Your set up is probably faulty. A static route on the second router (connected to the ISP) isn't required.

The proper set up looks like this:


Open Murus and hit the wrench > Static NAT





Choose the proper LAN and WAN interfaces. In your environment the WAN interface probably is en0 or en1 and your LAN interface is en3.
Then move the mouse pointer to your NAT group and hit the looking glass:



Remove the current IP/network address (in your case 10.0.0.25/32) and add the "NAT-client's" IP address (in your case 10.0.0.234/32) or a network address (e.g. 10.0.0.0/24).

You added the gateway's address (instead of the NATed network/host) by accident.

Add "ALL SERVICES" to the Allowed Internet Services.
Close the NAT window.
In the menubar > Firewall > Interface Forwarding choose "Enable".
In the upper right corner of Murus hit the start button (►) - just to be sure.
Test the NAT with the client.