NetBSD on Synology 107+

[portunak]

Greetings to the whole group.
I am a systems enthusiast, I use linux for several years in an exclusive way.
I’m trying to learn (never ends) with a little difficulty with the English language... so you’ll forgive me if I use a translator...

I am currently working on a synology 107+ that I have been doing for many years... I have put it back doing some hardware maintenance.
the problem was triggered when I realized that the official website was no longer available firmware for my model....
searching on the internet an alternative I came to NetBSD...
I followed this quida:
https://wiki.netbsd.org/ports/sandpoint/instsynology/

but my limitations arose when I failed to boot altboot.bin via TFTP....
I hope to find among you some advice and some tips to get ahead of this issue... and clearly increase personal knowledge...
I attach a bit of info in the following post...
thanks

Giuseppe