Nextpage & permalinks

I’m using the following permalinks

articles/%category%/%postname%/

I previously tried :

/%category%/%postname%/

However, when i try using next page, and use a url like

https://evan.tedfox.com/articles/evangelism-tracts/how-to-counsel-for-salvation/3/

It gives me a 404.

although the following url gives me page 1
https://evan.tedfox.com/articles/evangelism-tracts/how-to-counsel-for-salvation/

something like
/%category%/%postname%/page/
would make things fine, but that would give really ugly urls.

Anybody got any suggestions??