It appears there is no available firmware to download for this modem which means you will have to troubleshoot it by yourself. I would recommend using Public DNS servers instead of the ones provided by your carrier. To do this, connect the modem, go to Network and Internet in Control Panel and look for Network Connections/Adapters. Right click the connection for modem, go to IPV4 and assign the following DNS servers:
DNS Public no.1: 18.104.22.168
DNS Public no.2: 22.214.171.124
These are the public DNS servers provided by Google. You should use them instead of the ones provided by your carrier.