This article covers all the special Salesforce connections. If you are not sure what you should do, send the link of this article to your Salesforce administrator so he/she can provide you with the correct information for your login.
Custom Domain & SSO
This is fairly simple to identify: when you log in to Salesforce on your computer, check the address bar. If it shows something like https://mycompanyname.my.salesforce.com/... then your company is using a Custom Domain. These instructions are also for you if you get the message "Only SSO is allowed" at sign-in.
Access Custom Domain page
On the login page press Use Custom Domain (1)

Enter Custom Domain name
Simply type the name in the Custom Domain field (2) and then press Continue (3)

Sandbox and specific servers
DISCLAIMER : this setting shouldn't be used if you're not a Salesforce administrator, or unless an administrator told you to use them. Please be careful, or contact us if you have any doubt.
To connect to specific servers, click the top right settings icon (On android, choose Change Server in the menu).
Sandbox and Production server
You can switch between Sandbox and production server just by selecting the wanted server in the list (4).
If you need to enter a specific server, press the + button (5) and go to step 2.
iOS :

Android :

Specific server
Enter a label (optional) and type your specific host address (6), and confirm (7).
iOS :

Android :
