ip_conntrack: table full, dropping packet

Apparently your ip_conntrack table is full, you can review your table
with:

# cat /proc/net/ip_conntrack

The max number of connections is set in

# cat /proc/sys/net/ipv4/ip_conntrack_max

You can increase it with:

# echo "some_number" > /proc/sys/net/ipv4/ip_conntrack_max

Which might resolve your problem.