Trouble with support structure
I have a problem with the quality of the support material. I like to print with a new MK4 the shown part, but the support structure looks poor and get loose after some layer. The hole nozzle get dirty by filament and print fail. I use the default setting for MK4 with Input shapping. I also try organic support and try the change the setting for lower support layer from "0"to normal. Filament is PETG from Prusa.
On MK3S+ and Mini+ never saw this problem and MK3S+ have no problem on same part. The MK4 is new and it was the first print with support structure. 
RE: Trouble with support structure
Try posting in the Mk4 sub-forum.
RE: Trouble with support structure
I found input shaper profiles hit or miss, so I'd try without input shaper.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Trouble with support structure
As already sad you this should be posted in the MK4 Forum, but I think the problem is the support configuration. It seems you support is disattaching from you print.
Check the settings and maybe post a screenshot. I think bottom contact z distance is too high and I think you have no "bottom interface layers".
RE: Trouble with support structure
I post this problem her, because it is a new printer and a problem with "first prints troubleshooting".
Today I try a print where the support is only on the print bed. Same problem. I thought also about the setting " bottom contact z distance" but this will not be the problem when the support is based on the bed. When I look at the support, I have the feeling that the material flow is to low and the layer have a bad connection.
Now I try to print it without Input shaper....let's see.
RE: Trouble with support structure
@derkuchenmann
I had/have the same problems when it comes to support material.
I was in touch with the prusa support and it looks like they don't realy know yet how to fix this.
When ever possible, you should use organic support.
Now to my "Hotfix" for you.
Reduce the support speed to 50-60mm/s. That doesn't increase the print time tooooo much.
Then use the option "Synchronize with object layer". That, on the other hand, increses the printing time a lot.
See below the settings I'm useing.
As soon as I have the solution I'll let you know. But I don't think that's gonna be befor next year.
RE: Trouble with support structure
I just upgraded my MK4 to MK4S and I'm having a similar problem with support structures (in PETG). The support layers aren't sticking to each other resulting in loose strings that get caught on the hot end and dragged over everything. Printing with no support or with VERY small areas of support seems to work fine.
RE: Trouble with support structure
Looks like underextrusion. Try increasing filament temperature by 10°C
RE: Trouble with support structure
I know it has been some time ago, but have you manage to overcome the issue? I’m experiencing same thing.