There can be a couple of reasons why your NFS times out.
The most likely is the Firewall
On OS X check if NFSD is blocked. It should be allowed incoming connections.
Check your /etc/exports
Vagrant should have edited the file, if not, you may have some problems with permissions.
# VAGRANT-BEGIN: 501 e50326d8-bb53-49a6-8bc7-e4fac0e87807 "/Users/kevinsimper/myproject/coderwall" 10.100.100.10 -alldirs -mapall=501:20 # VAGRANT-END: 501 e50326d8-bb53-49a6-8bc7-e4fac0e87807
Try restarting nfs
sudo /sbin/nfsd restart