greptem2 theme – How to create an intext link to another page

Hi. I have a problem on my website: https://www.chaudey.net I am using the theme “greptem2”. The menu works well, but when I make a link in a page to another page of my site it doesn’t work. But it work if it is a link to another website. For example, in the page “my work”, in the introduction text there is a link to “contact page”, which doesn’t work. The html I wrote through the WYSIWYG editor (tinymce I guess), is simple: contact page.

So how can I make it work ? Can you please help me ? I have several other similar link, all the same problem. It works only if I put a link to another website.