Running 4.1.7 on ARMv7, Linux 4.9.103-odroidxu4
Observed that IPv6 was running even though the OMV web interface indicated it was disabled. The Web interface wouldn't disable it.
This worked:
edit /etc/sysctl.conf
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
net.ipv6.conf.eth0.disable_ipv6 = 1
Restart