We have Visio stencils HERE. Not sure how current or complete they are.
I've switched over to using google slides for all my diagrams nowadays. Not as technical as Visio or Lucidchart for sure. But, it has a simpler and more modern look for how I prefer diagrams to look. Not aware of any templates though. I tend to borrow product icons from here to make my diagrams.
Ryan / Meraki SE
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