Forms: It is recommended to practice how many fields on a screen for the mobile device and desktop browser

My website is using bootstrap, so it is sensitive and not adaptable.

I want to make a form that has many fields-> I have already divided into a section and cut unnecessary fields, for example, a section has 17 fields. The number of fields must be the same for the browser of mobile and desktop devices.

When I tested on the desktop, the user is not overwhelmed with the number of fields in a section, but when it comes to mobile devices, the user has a long scroll button to get (next -> to the next or previous section -> to the previous section).

Does anyone know from experience what is the best practice for a way like this? How many max fields should I have?