Linux Mint 20.3 features Cinnamon 5.2, a Linux kernel 5.4 and an Ubuntu 20.04 package base. LTS strategy. Linux Mint 20.3 will receive security updates until 2025. Until 2022, future versions of Linux Mint will use the same package base as Linux Mint 20.3, making it trivial for people to upgrade.
Screenshots - Download Linux Mint 21.1 - Linux Mint
There might be two possible solutions
Installing through LAN
You might need to set up a BOOTP + DHCP server then boot over the network via PXE, read here for detailed instructions
Alternatively,You could follow up the solution provided over here
Additionally you could do grub boot from iso,the detailed answers were provided over here
