Some Users / Clients Are Getting Locked Out

iThemes Security,

I am having issues with your plugin. Our users & clients can go to our website without login into and read information about our company, services and products. The only person that logs in is the admin.
We are getting some cases where a user goes to our website, and it seems that the iThemes Security plugin “Host Lockout” the user from our website and gives them our default error message of “Your computer have been locked out”. We trusts some of these clients so we have white listed them. Still unable to get onto our website and getting error message. Obtain the users ip address. Looked for ip address under ban, couldn’t find. Went to the database and search for their ip address to be locked out there. Couldn’t find.
We also know that it is the iThemes Security ip giving issues. We have turned deactivated every feature and etc. The only time that the they are able to get onto our website is when we deactivate your plugin.
We also know that it is based on the user’s ip address due to we have him go on his phone and using the phone’s internet, he is able to get on. Plus, it shows that error message on all internet browsers.
Is it possible that the Htaccess file could be too long for that user’s internet provider?
Is there a fix for this and how? Any suggesstions how to fix. We would love to use your plugin. It works great for security just only a few of our users cannot view our website.

The page I need help with: [log in to see the link]