[Raion]

Anecdotal, and certainly not helpful to your exact issue but:

I have had zero luck on any GNU/Linux distro with getting them to talk to IRIX over NFS. I use Solaris/Illumos, Both free and netbsd, and IRIX itself just fine, but there's probably differences in their config and security that prevent GNU/Linux from interfacing as easily.

Onto the things to check:

1. You need to be able to do NFSv3, that guide looks like it may be for NFSv4, which plain won't work on IRIX period. There's no support.

2. For NFS, you need to ensure RPCBIND, LOCKD, and MOUNTD are all enabled, running and that their respective ports are open.

3. I recall that the last NFS share I set up, I had to specifically put in my IRIX host addresses to /etc/exports to get it to work. That may not actually be necessary, but for some reason IP ranges didn't.