Client of Owncloud when Owncloud running on Synology

I installed Owncloud on my Synology NAS.
My NAS has a local IP.

When I select this local adress in the client of Owncloud, the Sync works just fine
My ID is @
This works fine when I am at home.

However I want this to work over the internet also.
I know I have to forward ports.
For other devices forwarding works.

Can someone tell me which ports I have to forward to get this to work?
A refer to documentation will also be fine.


from what i know it is usually port 80 and 443 which is used by a web server providing the ownCloud installation.

But from what i know the used ports of ownCloud depends on how ownCloud is installed on the device. For example on Synology it could be a completely different port then on a “standard” ownCloud installation.