[Urgent]Nextcloud client login issue

Nextcloud version : Nextcloud v15.0.11 snap
Operating system and version : Server - Ubuntu 18.04.3 LTS, Client - Any

The issue you are facing: On trying to connect to my nextcloud server from the Nextcloud client I get **** refused to connect. ERR_CONNECTION_REFUSED in the nextcloud connection wizard. This does not seem to exist while using owncloud client.

This issue seems to be related to another thread : link

Why is owncloud client able to resolve the url while nextcloud client cannot?