When using Nextcloud and Onlyoffice docker "The document could not be saved." is displayed

Hi all,

I am new here but I was hoping that you might be able to help me with a stubborn configuration error. I am using nextcloud and only office within docker containers, I am using the example provided for docker compose with mariadb from github with the following added for only office:

image: onlyoffice/documentserver
restart: always
- onlylogs:/var/log/onlyoffice
- onlycert:/var/www/onlyoffice/Data
- onlycache:/var/lib/onlyoffice
- onlydb:/var/lib/postgresql
- VIRTUAL_HOST=example.com
- LETSENCRYPT_HOST=example.com
- proxy-tier
- default

Everything works swimmingly except that when I open a document with only office I receive the below error:

The document could not be saved. Please check connection settings or contact your administrator. When you click the OK button, you will be prompted to download the document

I am not sure if this is the right place to post or not but any help would be greatly appreciated.

Thankyou in advance