Hey TLC34,
We see that you're getting a message stating "Cannot Verify Server Identity". This seems to happen when you're using an app that uses Location Services. We will do our best to assist. If there is an active VPN being used, we suggest temporarily disabling it to see if the message still appears. Also, profiles showing in Settings > General > Profiles & Device Management. If you do not see that option in Settings > General, then there are no profiles installed.
If that doesn't resolve the issue, check to see if it's the same certificate when it happens. If so, you would want to contact the provider of that certificate to resolve the issue.
If it happens with multiple accounts, reset Network Settings. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that they've used before.
Best regards.