Nextcloud clients not working anymore in Ubuntu (16 - 18 - 20)

I have not been able to use Nextcloud anymore for several months, as my Nextcloud clients won’t work anymore.

I have not been able to find a situation exactly similar to mind when searching on the web either.

I am using Nextcloud installed on a Gandi hosting.

I use Ubuntu installs on my desktop and I had Nextcloud client on my android smartphone where it used to work too.

It had worked fine until the version 2.4 of the Nextcloud desktop client.

Since the versions 2.4 where upgraded, this is what I have been facing each time I tried to get a connection between the client and the server:

1 :
2 :
3 :

I would be curious to know if someone has a lead on what can be going on (the server logs didn’t help me either as there is not mention of nextcloud in them, whatsoever).

Meanwhile I have started using another open source cloud, and other ways to sync files, calendar and contacts, but, this is really annoying.

Thanks for future answers.

Best regards,

They have released a new version of the client