cPanel will sometimes show the error "IP address has changed!" while you are trying to connect.
Some ISPs [Internet Service Providers] have short DHCP life times, or your IP may change if you are using another computer to access cPanel. This can cause the behavior described, and these types of connections do not work well with cPanel. You can try several things to try to fix the issue:
1. Navigate in WHM to Main >> Server Configuration >> Tweak Settings >> Security tab
2. Look at the section called "Cookie IP Validation" and if you click the ? symbol you can read more:
"Validate the IP addresses used in all cookie based logins. This will limit the ability of attackers who capture cPanel session cookies to use them in an exploit of the cPanel or WebHost Manager interfaces. For this setting to have maximum effectiveness, proxydomains should also be disabled."
3. Change this setting to "loose" and it should cause the reauthentication frequency to diminish or go away. To disable it go to WHM > Tweak Settings > Cookie IP validation and set it to "disabled"
4. Please also see cPanel documentation on disabling proxydomains.