It´s always a challenge to get the Visio Stencil´s to do nice and clear Diagrams, so i decided to compile them here.
Juniper
Product Icons & Visio Stencils
Cisco/Meraki
Stencil Listing
Link to Cisco Network Topology Icons
Avaya/Nortel
Avaya Networking
Avaya Legacy and Miscellaneous Stencils
Avaya Legend Tools
F5
Check Point
https://www.cocheno.com/2012/09/visio-stencils-para-checkpoint/
Palo Alto
Fortinet
DELL/FORCE10
HP PROCURVE/3COM
Brocade/Foundry
Riverbed
Citrix
Amazon
Azure
Microsoft Azure, Azure Pack and Office 365