I have an existing wifi network and a Google Nexus 5 (un-rooted, stock android) with 3G data connection.
I would like to tether my mobile to share internet to all devices in existing network which have a custom route or proxy, maintaining default route for all other devices. This existing network also has another fixed connection (default route).
This means Android should effectively connect as a guest to existing wifi network, maintaining 3G/4G data connection and allow data to traverse through its mobile network while providing Gateway / NAT function for any devices which have an appropriate route / proxy set.
Configuration for the other devices (setting routes or configuring proxy) can be managed by hand (manually) as I am a capable network administrator.
As this is typically a consumer device, is this possible? and can anyone provide suggestions on software / howto's / information for this? Technically, my knowledge of computers networks and linux tells me this should be 100% possible, and relatively simple to achieve.
The cost of data here is not in question, I understand that connecting a mobile to an existing network could use a substantial amount of data and may impact my contract and data allowance.