Effective accessing the AOL mail on iPhone or any other device depends on several factors. First of all, you should have a stable and high-speed Internet connection, the aol smtp settings and IMAP settings should be correctly configured and your network router must have enough bandwidth to manage multiple devices on a network. If nothing worked out then try these quick fixes.
• Turn on and then turn off the flight mode.
• Restart the router.
• Make sure you have an active data pack (for cellular plan users).
• Try resetting the network settings.
• Lastly, consult your network provider or call the email experts.