When i mount via nfs on boot, and then look at what options being used, here there are.
And when i test to mount with these again it works.(not the same error message as you)
I not shure what options that make it!!
rw,relatime,vers=3,rsize=524288,wsize=524288,namlen=255,hard,
nolock,proto=tcp,port=2049,timeo=70,retrans=3,sec=sys,local_lock=all,addr=10.42.0.1
Have tried some options and it seems that then i use option addr=(nfs server address) and option nolock it works.
mount -o addr=10.42.0.1,nolock -t nfs 10.42.0.1:/home/patrik/picore temp