I have a single uplink with my ISP at a data center. I have 2 routers (CISCO 3850). How do I connect these routers to that uplink WITHOUT a network switch? That switch will be a single point of failure.

Is there something like ATS for ethernet. I mean one ethernet IN port and two OUT ports and this device route packets to primary OUT port if it is active (if there is a link) and route to the secondary if it is not active. Will be even better if it is passive device.

I don't mind to use a network switch between the routers and uplink but it has to be like 10 times more reliable that normal switches. Is there such thing as super reliable network switch where everything is redundant? I do know that such network switches with dual CPU card, dual power supplies, line card exist but they are huge and pricey. Are there cheaper fully redundant switches ?

Is there another solution ?