cannot bind to local IPv4 socket: Cannot assign requested address

inet 169.254.210.0

Yeah. That’ll be that you’re needing an interface with that address assigned.

ifconfig

Going from memory, I believe that if you’ve got ifconfig available and this is a Linux system and you need to keep the address on the current interface to keep the system connected to the Internet or something, you can use something like ifconfig enp7s0:0 10.10.10.3 to use an interface alias, use both addresses (169.254.210.0 and 10.10.10.3) at the same time. Might also need ifconfig enp7s0:0 up after that. That being said, (a) I don’t think that I’ve set up an interface alias in probably a decade, and it’s possible that’s something has changed, (b) that’s a bit of additional complexity, and if you aren’t super familiar with Linux networking, you might not want to add more complexity if you don’t mind dropping just setting the address on the interface to something else.

Probably an iproute2-based approach to do this too (the ip command rather than the ifconfig command) but I haven’t bothered to pick up iproute2 equivalents for a bunch of stuff.

EDIT: Sounds like you can assign the address and bring the interface alias up as one step (or could a decade ago, when this comment was written):

https://askubuntu.com/questions/585468/how-do-i-add-an-additional-ip-address-to-an-interface-in-ubuntu-14

To setup eth0:0 alias type the following command as the root user:

# ifconfig eth0:0 192.168.1.6 up

So probably give ifconfig enp7s0:0 10.10.10.3 up a try, then see if the TFTP server package can bind to the 10.10.10.3 address.