Unable to associate client (Window 10 desktop and Android apps) to a server

Greetings,

First off, I like to thank nextcloud/this community for the wonderful software/support. I am relatively new to nextcloud but do have basic skills in linux. I recently installed nextcloud with mariadb, nginx and letsencrypt in my ubuntu 18.04 server through docker/docker-compose, and everything works fine through a web browser.

To set up nextcloud through docker/docker-compose, I basically followed this guide (https://blog.ssdnodes.com/blog/installing-nextcloud-docker/), with the exception that I used nextcloud:apache as the docker image. One particularity of this guide is that he created a docker network for internal communications between nextcloud/maria/nginx/letsencrypt.

The version of the docker images are:
nextcloud: 18.0.4
nginx: 1.17.6
mariadb: 1:10.4.12+maria~bionic

After verifying that it works well through webGUI (that I can upload file via drag-n-drop), I proceed with installing clients for Windows-10 desktop and an android device. This is where I am encountering problems, I seek your help.

In both cases, during the Connection Wizard, I entered the server address and clicked on “next”. The web-browser (google chrome) will bring up the login window, in which I entered the credential to login to my server. In the next Window, I “Grant access” to my Nextcloud account, but it simply hangs there.

If I check my nextcloud server log, i see the following (every 30 seconds):

‘’’
172.20.0.3 - - [27/Apr/2020:17:02:06 -0400] “GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1” 200 4637 “-” “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.122 Safari/537.36”

172.20.0.3 - - [27/Apr/2020:17:02:06 -0400] “GET /csrftoken HTTP/1.1” 200 826 “-” “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.122 Safari/537.36”
‘’’

and nothing else.

As this happens when i tried to install the client both in windows 10 desktop and an android device, what server setting is causing this issue?

If anyone can shed lights into how I can begin to debug this issue, it would be very much appreciated,

regards,