walls that don't stick together

[vincent2023 0]

[gr5 2,027]

That's usually underextrusion.  I'd like to see the part from the top also.

[vincent2023 0]

I have tested with 185/200/240/260 degrees nothing change.

[gr5 2,027]

underextrusion isn't always temperature related.  It could be you have something wrong with the feeder or the nozzle.  If you can show a photo of the top of the part it should be more obvious if the problem is underextrusion.

 

Also if you slice for 0.4mm wide paths but use an AA 0.6 core.

 

I'd really like to see the top of the part zoomed in as well as the photo you already published.

 

I assume this is an AA 0.4 core.  You could try the other core - S5 printers come with two AA 0.4 and a BB 0.4.  Sometimes the nozzles get partially clogged - the plastic can caramelize on the inner walls of the nozzle and turn your 0.4mm hole in your nozzle into a 0.3mm hole.  Then you get mild underextrusion like in your photo.

 

Especially if you are raising the temperature so high - this can cause much more rapid caramelization.