Can't connect to LAN and internet at same time
This is usually caused by having the wrong subnet masks specified for the networks. 

In your case with IP-adresses 10.100.8.1 and 10.125.32.1 you'll probably the subnet mask set to 255.0.0.0 (/8) for both networks - that is incorrect.

Change the subnet masks so they are for example 255.255.0.0 (/16) instead, and you'll be able to route normally.

Remember to only set a default gateway in the subnet associated with the interface you actually want to use as an Internet connection.