Coffee grind for dolce gusto or Nespresso (refillable) capsules?

Miscellaneous and Personal Stuff I Must Share
1

I have a Dolce Gusto capsule bearing coffee maker …

this model:

and while I do use the “commercial” capsules (both D-G and 3rd party), every now and then I use my permanent (refillable) capsule:

the “option 2” in this pic:

so now my Q to the coffeonados:

what kind of grind (or other parameters like “roast”) should I shoot for to get the best out of my “homebrew capsules”?

any pointers/tips and tricks are warmly welcome !!!

2

While I can’t address your machine, I’ve found by experiment — with refillable pods in a Keurig — that the finer the grind, the stronger the brew (presumably because it takes longer for the water to make its way through). While I’m anything but an aficionado* I do like my coffee fairly strong, so I settled on something between “fine” and “espresso.” Your mileage will likely vary.

* I cut my teeth — almost literally — on backstage coffee, which generally varies between “sludge” and “boiler scale remover.”