WP Admin Problem Logging In (URL NOT FOUND)

Hi,

WP admin problem. As soon as I try to log on the admin url shows a URL error message. Last week I downloaded the Solid Security plugin and made adjustments. Everything was working fine. The next day I log on and I download the MainWP plugin, made adjustments and everything is fine. The following day I log on and I get the error?message. I talked to my hosting company and they said to turn off each plugin one by one. I only have two so once I turned off Solid Security Plugin the site admin works and I don’t get the error message. There is something happening with Solid Security Plugin that is not working. Have you guys had this problem with other customers before? If not, is there a solution?

Error Message Being Displayed:

Not Found

The requested URL was not found on this server.

However when plugin is deactivated it works perfectly.

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