I'm having this exact same issue on both 16.04 and 16.10, with two laptops.
My nfs shares are mounted via AutoFS service (/net -hosts) and that has been working fine for many years on previous releases.
When shutdown hangs, I can see message by hitting Esc says "Stop nfs ... nn m nn s/1m30s" some kind, then when the first number increases close to the 2nd ones. the 2nd one will increase too, then repeating like that forever.
I'm having this exact same issue on both 16.04 and 16.10, with two laptops.
My nfs shares are mounted via AutoFS service (/net -hosts) and that has been working fine for many years on previous releases.
When shutdown hangs, I can see message by hitting Esc says "Stop nfs ... nn m nn s/1m30s" some kind, then when the first number increases close to the 2nd ones. the 2nd one will increase too, then repeating like that forever.