RE: SSL Certificate installation in Nav 2018 Mobile Client
Certificates is validates web site adress and encrypt all data across from client and server.
If you use certificate like nav.yourdoman.com you can not allowed to use any other domain or ip.
If you are using self signed certificate, please change it with letsencrypt free certifiate and get a proper web adress.
Here is a turtorial about this you can use win-acme client. all process takes 5 minutes.
But if your main problem is based on internal or external network. You have to adjust your firewall or dns adressess
Sometimes in company wifi is not solving your domain name than you want to use ip adress but it's not possible
If you have any further question please free to ask i am also adding letsencryp turtorials link
www.hougaard.com/how-to-use-lets-encrypt-certificates-with-dynamics-nav