Your problem is probably that you are operating in a different Subnet (IP address range) from the town's LAN. The Subnet Mask address of 255.255.255.0 will prevent addresses with a different third "octet" from communicating, i.e. 192.168.70.x addresses won't communicate with 192.168.10.x addresses. Can you not operate your devices in the truck with 192.168.10.x addresses, using firewall software to block unwanted access?
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