Assistance Required - submissions could not be sent to their external endpoints

Hello all,
I need assistance with an REST -server issue, my form is not receiving submissions. the form used to receive submissions and currently has over 200 successful submissions. i have checked the forms validity and its valid.
Attached are screenshots of the issue.
Thank you.

Welcome to the community, @henry_yakuba! Could you let us know the server you are using? I could then check the same at my end to see if I am able to send my data through the REST API.