LAN gets disconnected from network when modem gets connected to ISP

Hi guys,

I have a broadband modem to connect the ISP, but once it connects, the LAN network is not accessible. I can still ping the gateway of the LAN IP segment, but not the other LAN IP segments. As if the computer is disconnected from the network. Once I disconnect from the ISP, the LAN network is accessible again.

The modem is not intended for internet use but for remote desktop connection through the ISP.

Hope there is a work around this.

Thanks.