2 separate ethernet connections into 1 desktop

To preface my questions, I am NOT trying to combine 2 ethernet connections to get any bumps in speed. The speed of both of my fiber ISPs is excellent.

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The Problem

I have 2 ISPs running into my house on 2 separate routers. I have Ethernet cables from each router running to my desktop, but I only have ONE Ethernet port on the back of my desktop.

If one of my connections slows or goes down, I have to get up and change out the cables.

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I want to be able to connect both Ethernet cables to the 1 computer and be able to manually switch between the 2 or (if it is possible) also have the computer drop the slower or down connection and reconnect with the other.

Will a male splitter with two female connectors allow me to run both of the Ethernet cables to the computer, or would it be best to have a USB/Ethernet adapter to connect the second cable to the desktop?

I don't know how any of this works, and before I spend any money on splitters or adapters, I'd like to know what is possible and how to do it.

Thanks in advance.

NOTE: I'm using Win10 Pro - 64 bit OS - 32GB RAM - 13th Gen Intel® Core™ i5-13400   2.50 GHz

You really need a router with Dual-WAN capabilities so that you can choose one of those incoming connections as "Fallback". The issue with two NIC's on the desktop means that you would have to disable the one that you want as fallback and end up in the long run having issues that can crop up from that stetup.

You'll need another network card

Thanks. And then what?  Windows 10 will make those switches automatically between the 2 connections?

You'll need another network card

 
Thanks. And then what?  Windows 10 will make those switches automatically between the 2 connections?

For reference purposes, here's what Windows is capable of doing in terms of switching network connections:

Understanding and configuring Windows Connection Manager

https://learn.microsoft.com/en-us/windows-hardware/drivers/mobilebroadband/understanding-and-configuring-windows-connection-manager

I agree what you're really looking for here is a router with Dual WAN capability. Luckily, there are plenty of choices these days.