@arhancock 

Please note that TL-R470T+ is a NAT router not a traditional router. If you need data transfer between LAN and WAN, you need to think about the NAT. 

You still need to think about subnet mask. For example 10.251.10.11/8 and 10.10.10.4/8 are in the same subnet and doesn't need routing. But for 10.251.10.11/24 and 10.10.10.4/24, it needs routing.

For example,

PC1(10.251.10.11/8)------|

                                        |------(LAN 10.10.10.1/8) R470T+

PC2(10.10.10.4/8)---------| 

Doesn't need routing. PC1 and PC2 can access each other.

For example,

PC1(10.251.10.11/24)------(LAN 10.251.10.1/24) R470T+(WAN 10.10.10.1/24)---------PC2(10.10.10.4/24)

PC1 can access PC2. But PC2 canot access PC1 because NAT exist.