Lock down IPs for server access but allowing some users mobile access.

I am trying to lock down the IPs that the majority of users can authenticate from. I can limit the webclient through access control but the server will still respond to other authentication methods which is what I would like to protect against. For example. 100 users. 90 cannot use the system unless on a specific site/IP address. They will either be using webclient and/or Outlook. I would like to prevent any external IPs from attempting to authenticate these users credentials from external IPs by any type of methdod. The other 10 need to be able to use any authentication method from any possible IP except for intrusion prevented blocked IPs such as mobile phone app, laptop, outlook etc. We are seeing a large quantity of authentication attempts for some valid user accounts. I have looked at the help sections, but I am not sure if I am missing something that could achieve this.

Thanks in advance if anyone can point me in the right direction!