fortigate 60e Conflicts with 'wan1' subnet

[dingKQ]

Our ISP gave us 10.1.10.* for ip ranges, the VoIP phones are using these.  Yesterday I was adding the fortigate 60E as firewall, while try to config the "internal" (LAN) to be 10.1.10.99/255.255.255.0 (using 6.0.4), I got "Conflicts with 'wan1' subset' error, I looked at the WAN1, it is 10.1.10.184/255.255.255.0.  Any suggestions would be much appreciated!

[ede_pfau]

As the FGT is a router, you cannot have the same subnet address on two different ports.

Your ISP gave you private addresses - which is at least uncommon - from the 10.1.10.x range. For the LAN, you need to choose a different range, like 10.1.11.1/24 for the 'internal' port. The FGT will do the routing between both subnets, policies permitting.