Getting Zabbix agent on Zabbix server is unreachable for 5 minutes error

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Hi,

I am new to Zabbix tool, I wanted to monitor some of the docker containers that I am running in my local vagrant setup.
I am trying to monitor some of the platform components and one simple application running on top of that.

I am trying to integrate Zabbix-server with PostgreSQL, Zabbix-agent, and Zabbix-web-nginx.

I have run following run commands -

zabbix-server:
docker run --name zabbix-server -t
--net plat_setup_default
-e DB_SERVER_HOST="192.xxx.xxx.x"
-e POSTGRES_USER="postgres"
--link postgres: postgres
--link zabbix-agent:zabbix-agent
-p 10051:10051
-d zabbix/zabbix-server-pgsql:latest

web-nginx:
docker run --net plat_setup_default --name zabbix-web-nginx-pgsql -e DB_SERVER_HOST="192.xxx.xxx.x" --link postgres: postgres
--link zabbix-server:zabbix-server -e POSTGRES_USER="postgres" -e ZBX_SERVER_HOST="172.18.0.1" -p 18195:18195 -d zabbix/zabbix-web-nginx-pgsql:latest

Zabbix-agent:
docker run --net plat_setup_default --name zabbix-agent --link zabbix-server:zabbix-server -e ZBX_HOSTNAME="zabbix-server" -e ZBX_SERVER_HOST="172.18.0.18" --privileged -d zabbix/zabbix-agent:latest

Please note that I am not sure about the ZBX_SERVER_HOST and ZBX_HOSTNAME variable here, I have done docker inspect of server and added the IP in agents ZBX_SERVER_HOST while running it.
My all the services are running in the same network which is 192.xxx.xxx.x.

I am getting following issues while deploying and running the Zabbix server, agent.
--------------------------------------------------------------------------------------------------------------------------------
zabbix-agent logs:
59:20181205:133513.767 no active checks on server [172.18.0.18:10051]: host [zabbix-server] not found

zabbix-server logs:
155:20181205:133513.767 cannot send list of active checks to "172.18.0.20": host [zabbix-server] not found

Attached are the snapshots of the Errors I could see on Zabbix UI.

Quick help will be really appreciated.