Ok here's the setup:

 

• Remote location visited every 3-6 weeks for a few days
• Vodafone Huawei (556?) Router
• DHCP devices (IP Camera, Raspberry Pi) accessed via port forwarding from Internet

When at the location the router works fine for both wired and wireless devices, laptops, phones etc. However, exactly 7 days after leaving the location, the router goes dark on the Internet side.

There are still connected devices (via wireless) on the local side, and ftp traffic still going from the devices, through router, to Internet sites.  However the router does not respond to any internet traffic whatsoever.

Any thoughts / suggestions / fellow sufferers / wizards out there?

Cheers,
G.