--On Tuesday, February 16, 2021 12:00 PM +0530 Thomas Stephen Lee lee.iitb@gmail.com wrote:

The solution should be a software one without acquiring new hardware. What is ideal is the bandwidth of two connections and half bandwidth when one link is down.

The search term you're looking for is "NIC bonding". Here's the first hit I get from Google:

https://www.enterprisenetworkingplanet.com/linux_unix/article.php/3850636/Understanding-NIC-Bonding-with-Linux.htm