New to 3D printing and am truly a novice. I was printing a wallet I found in Printables. I used Bambu PETG basic. The wallet was printing fine when on the second layer of infill it began to clump and string. I have dried the filament in a dryer and used the presets in the STL file. I made two attempts. Any guidance or advice would be welcomed.
Change to rectilinear or gyroid infill or another infill that doesn’t cross lines.
Grid infill hits and crosses the lines going one way when it prints the lines going the other way, which doesn’t work with PETG because it is too sticky.
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Thank you for responding and sharing your knowledge. I appreciate that experienced makers are willing to share their expertise with us who are new to the hobby.
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Make sure your Sparse INFILL and Internal solid infill speeds are set appropriately. Same as Inner wall or Outer wall may be a good place to start. Too much speed and the petg seems to just shred like that.
Hi, that sucks, but starting with PETG is also not the easiest.
An STL file contains no print settings, only the model geometry. So I guess, by default settings, you are referring to the Default printer settings along with the PETG Basic filament profile.
May I ask which printer you are using? A P1P or P1S?
I can see some signs of uncalibrated Pressure Advance and Flow settings.
Did you try to run both calibrations found in Bambu Studio?
I guess what I stated shows how inexperienced I am. I did try running flow dynamics calibration settings, but to be honest with you I don’t know exactly what I’m doing. I’m using a P1 S system. Thank you very much for responding and educating me
Olendorf, thank you for your advice. I’m still learning how slow I can go or how fast I need to go. There seems to be a learning curve and I’m a wee bit behind
Why didn’t anyone suggest that he raise the filament temp? That’s looking to me like an adhesion issue caused by incorrect temp settings.
Ask me how I know. 
That is looking like you may be using the wrong profile. Just to be safe, check these two settings.
Try bumping it up to 265 and see if it helps.
It will be found under Filaments
Then scroll down and make sure your max volumetric flow is set to some number under 15mm³/s
Thank you for the detailed response. I have been learning a lot from the responses I have received. I will definitely try this. I printed a temp tower that topped out at 265 Celsius which did appear to be the best print visually. I will try 265. I work midnights and will have to try again later. Again thank you for sharing your insights with me.
No worries, we are all learning. 
I suggest starting with the flow rate calibration. It’s a bit easier and will influence the flow dynamics anyway.
The calibration will print some test pieces so you can see which one has the smoothest surface. (Only observe the middle of the pieces; the potentially rough edges will be dealt with in the flow dynamics calibration)
When running the flow dynamics test, it’s not always easy to get a clear result.
I suggest starting with a filament color that is highly contrasted relative to the build plate. The print result of the Flow Dynamics calibration should be a bunch of lines, all having two spots: one where the print head accelerates and one where it decelerates. The difference in these lines (or K Values) is how much/rapidly your extruder pushes the filament while undergoing speed changes.
You will have to pick the smoothest line in both spots.
I use my phone’s camera to get a detailed look at each line.
Doing both of these calibrations should get you closer to a good print result.
Keep in mind that you will have to do this calibration for every new filament type you get. In some instances, you can even see changes when printing with two roles of the identical type and brand of filament.
I agree with setting the max volumetric speed to a max of 12 mm³ or even lower. I usually run PETG at 8 mm³, but that also comes with a slight print duration penalty.
Upping your temperature might help with layer adhesion, but it will eventually become a problem for overhangs. I would rather try lowering the cooling speed first and observe if that helps.
Thanks to all who responded.