DOI Connection Error from behind firewall though connection check in network preference is successful

Help
1

#jabref5.12
I have set proxy configuration including authentication credentials in Preferences → Network, and the “Check Connection” button reports “Connection Successful!” message.
However, new entry based on ID set to DOI, and a valid DOI generates a “Error message Connection error” error.
Where should I be checking / correcting settings?

2

I simply don’t know the answer to this question. Hope you got it right eventually?