Registration to drops randomly

I have set up a new FreePBX and everything works fine except for the registration of the trunk to randomly keeps on dropping. I have already set it to retry interval 60 seconds. To register again I have to go in and save the truck and it reconnects. Any idea why the registration is dropping and not re-registering?

Here is what I see in the Asterisk logging when the registration drops

[2017-12-11 00:36:17] WARNING[9015]: res_pjsip_outbound_registration.c:908 handle_registration_response: Fatal response ‘401’ received from ‘’ on registration attempt to ‘sip:[email protected]:5060’, stopping outbound registration

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