How to access from one instance to another using molecule - mongodb

Question

I'm trying to use ansible-mongodb-cluster scripts to create a mongodb cluster.
I've edited hosts in order to have just a primary and a slave.
I use molecule with vagrant to test it.
this is my molecule.yml
ansible:
playbook: 01_create_cluster.yml
verbose: vvv
inventory: hosts
vagrant:
platforms:
- name: centos
box: centos/7
providers:
- name: virtualbox
type: virtualbox
options:
memory: 512
cpus: 2
instances:
- name: mongo1
ansible_groups:
- mongo_servers
- mongod_primary
- mongod_slaves
interfaces:
- network_name: private_network
type: static
ip: 192.168.80.1
- name: mongo2
ansible_groups:
- mongo_servers
- mongod_primary
- mongod_slaves
interfaces:
- network_name: private_network
type: static
ip: 192.168.80.2
and this is hosts inventory ansible file:
[mongo_servers]
mongo1 mongod_port=27017
mongo2 mongod_port=27017
[mongod_primary]
mongo1 mongod_port=27017
[mongod_slaves]
mongo2 mongod_port=27017
the problem borns when, after primary is created and replication is activated on it, slave trying to connect to the primary:
"MongoDB shell version v3.4.4",
"connecting to: mongodb://mongo1:27017/",
"2017-05-25T15:38:51.399+0000 I NETWORK [thread1] getaddrinfo(\"mongo1\") failed: Name or service not known",
"2017-05-25T15:38:51.400+0000 E QUERY [thread1] Error: couldn't initialize connection to host mongo1, address is invalid :",
"connect#src/mongo/shell/mongo.js:237:13",
"#(connect):1:6"
it doesn't know mongo1 host.
Even if i add in /etc/hosts the relation
192.168.80.1 mongo1
it says me that Destination Net Unreachable
how can i solve and let every VM "see" the others in the network?
EDIT
ping goes in timeout and telnet too
EDIT2
This is traceroute
[vagrant#mongo2 ~]$ traceroute mongo1
traceroute to mongo1 (192.168.80.1), 30 hops max, 60 byte packets
1 gateway (10.0.2.2) 0.191 ms 0.111 ms 0.063 ms
2 192.168.93.254 (192.168.93.254) 0.614 ms 0.716 ms 0.710 ms
3 10.17.254.1 (10.17.254.1) 3.410 ms 3.366 ms 3.316 ms
4 93-57-16-193.ip162.fastwebnet.it (93.57.16.193) 5.409 ms 5.384 ms 5.340 ms
5 93-54-33-65.ip127.fastwebnet.it (93.54.33.65) 21.192 ms 21.135 ms 21.084 ms
6 10.2.7.101 (10.2.7.101) 10.390 ms 2.447 ms 2.318 ms
7 10.254.20.77 (10.254.20.77) 2.228 ms 10.254.20.73 (10.254.20.73) 2.171 ms 2.045 ms
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[vagrant#mongo2 ~]$

Answer 1

I solved adding two other configuration to the molecule.yml:
interfaces:
- network_name: private_network
type: static
ip: 192.168.80.1
auto_config: true
options:
append_platform_to_hostname: no
auto_config: true
and
options:
append_platform_to_hostname: no
now if i ping the other vm, they reply successfully!