Mobile display : wordpress source code appears on mobile device


I have an issue when I access to my website on mobile.
The wordpress source code appears and the menu is not the same as on a computer or a tablet.
The website works well on tablet and computers.

Website :
Theme : Lambda
Navigator: Safari and Chrome same issue on private navigation
Wordpress 4.7.5 and plugins are up to date.

Anyone can help me with?

Thank you so much.