Guest WIFI connects to wrong IP and subnet

Are you certain it's 43 and not 42?

I can't speak for every configuration, but I believe on newer HughesNet systems, the 192.168.10.0/24 block is reserved for locally connected devices (such as the WL3000 and quite possibly the mesh units) in the routing table. The 192.168.42.0/24 block is reserved for user devices, which is why DHCP is defaulting to that.

Therefore, anything routing through the wifi or ethernet ports should conform to 192.168.42.0/24 IPs. I may be remembering it wrong, but I think it's been this way since they moved to the HT3000W modems. I would not recommend messing with the modem's routing table, because it could feasibly render the local LAN unusable and then require tech support to get it working again. This is especially true if you use the wifi to administer the modem.