No internet due to iptables What could be?

Question

iptables

There is a server with ubuntu server 16.0.4
iptables is configured by default, incoming connections are dropped
, there is a virtual network for virtual machines ...
and portforwarding is configured
such a trouble when iptables is enabled on the host, the Internet disappears and on virtual machines it is)
what could be the problem?
all local connections are allowed ... you can connect to the host remotely, but there is no Internet from it (

Answer 1

Apparently, incoming packets are dropped, tk. there is no rule to skip them. Allow all incoming connections in ESTABLISHED,RELATED state to all directions:

iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT