Such a thing exist? [Network/Redundency]

[firehawk]

So, hear me out.
I have internet connected through a sky router on their "fibre" service.
I also have a cisco Linksys E4200 router connected to the router. all works fine but that's not the issue.

I want to know if there is some way, some method, whatever it is - to allow me to "switch" between internet connections? Kind of like a failover.

The backup internet, I want it to be of a 3G/4G Simcard or something that I can connect (somehow) to the router and it would kick into action if internet has been found to be disconnected for some period of time.

is there something like this that exists or can be built (easily)?

interested to know your thoughts.

 

[freshdeniability]

Automatic switching? Doing it manually is fairly straightforward, get both connections up using routers of some kind, both with different IP's - then just switch the default gateway to use each of them.

 

[firehawk]

Hey.
Not sure I follow?

I have DHCP enabled on the main router
DHCP is disabled on the Linksys router and uses the DHCP assigned from the main router for other devices connected to it.
It uses a static IP which points to the main rotuer including DNS/gateway.

what I need ultimately is this setup BUT if possible, a device or something that can be plugged into the router and if the main internet drops, for this device to kick in and use a 3G/4G simcard for internet access instead so all traffic goes through it.