This article will provide you more details and information regarding how to whitelist an IP in Matrix:

1. Navigate to the Settings section and then Security tab:

2. Next click on "Create" under the IP List section:

3. Next input your IP you wish to whitelist and a description, click Save to whitelist the IP. Alternatively you can also whitelist a Country wide IP from the "Add country" section from the same window:

To remove an IP from the list, click on the action button next to it and select Delete:

Additionally from the "Security Log" section you can see who has added/removed IP's and made changes:

Lastly from the "Failed Login Attempts" section you can also see who has failed to login and from where: