that is bit strange. if default route and internal routes are added it should be able to access internet. can you try traceroute and check where is it getting dropped?
can you able to ping from VLAN 10, 20, 30 to 184.108.40.206 or 220.127.116.11
also post traceroute information to 18.104.22.168 22.214.171.124
what is the DNS Setting at PC ?
I do not think it's a DNS problem, because from VLAN 10 I do not have a problem
from VLAN 20,30,40 I can go to the external address of the Modem but I do not go out anymore it's like my vlan addresses are not routable
for the DNS I use 126.96.36.199 I even used other DNS of the operator who walk but without success