Hi @prime3045
If users are getting redirected to 127.0.0.1 might be the login honeypot ( WP Security > Brute force > Honeypot) enabled and you have cache also enabled which is making issue. Please try disable login honeypot or cache and check.
Other reason might be their IP blocked. It might be the cache enabled that is why they can access other pages. Go to WP Security > Dashboard > Permanent block list > There the User IP address is not blocked.
Also please cross check the correct IP detection method is set other wise might be the server blocking itself.
WP Security > Settings > Advanced settings tab have IP address detection settings there you may cross check set the right IP address detection which matches https://whatismyipaddress.com/ IP address
Regards