Hi!
passbolt.dev has to be reachable from your other hosts. Seems like you are using /etc/hosts as the “DNS” method to access your passbolt instnace. That is why when deleting the line from your local /etc/hosts you can’t access your passbolt instance.
In order to access passbolt.dev from your other nodes you should add an entry to /etc/hosts in all the nodes that require access to the passbolt instance.
Another approach would be to buy a non private domain name in any commercial domain name registrar.