Can you please write a guide.
What are you trying to do exactly, and why?
I need a tftp access to external device from AppVM.
Welcome @zack. Before asking if someone could write a guide, you should first look into it a bit yourself and explain what you tried and why it didn’t work.
The best place to look is the Documentation of Qubes:
If you looked there you would find the “guide” you are probably looking for.
But be aware that it is a bit challenging and if you are new to Qubes, it may be better to spend some afternoons first reading the documentation so you know what you’re doing.
Also, if you need tftp, you probably only need to open one or two ports. Not all of them.
Best of luck!