Host OS Ubuntu 15.10
Guest OS Ubuntu 14.10

Using Vagrant with nfs and Virtualbox and static ip on the private network.

It is working perfectly except that after having suspended the host OS, the entire guest OS will be unusable. This does not happen when using the normal virtualbox shared folders.

It's not only the nfs shared folder that is unusable, the entire OS is hanging. Even syslog does not seem to see much action. This is syslog on the guest, from waking up until vagrant halt is completed.

Feb 26 07:15:33 vagrant kernel: [ 8375.252989] e1000: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
Feb 26 07:16:11 vagrant kernel: [ 8413.109832] nfs: server 192.168.33.1 not responding, still trying
Feb 26 07:16:38 vagrant kernel: [ 8440.687476] nfs: server 192.168.33.1 not responding, still trying
Feb 26 07:17:01 vagrant CRON[3776]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)
Feb 26 07:20:33 vagrant rsyslogd: [origin software="rsyslogd" swVersion="7.4.4" x-pid="753" x-info="http://www.rsyslog.com"] exiting on signal 15.

How can this be fixed?
How should I debug it?