Weird, I connect to my companies VPN from inside my network, and my own VPN from outside through my double NAT all the time without issues. I can’t comment on VoIP setups though as I don’t use them.
If you (not specifically you Scott, everyone else) have a bunch of IOT devices, I would strongly recommend reading the Three Dumb Routers article.
I disagreed with that article. It is a massive kludge for little increase in security. For the price of two crappy consumer routers you can get a Fortinet and subscribe to the cloud protection. Now you have real perimeter security.
With the Fortinet you can have as many VLAN's as you want and setup security policies for traffic between the vlan's
If you can't bring yourself to spending that much you can pickup a Microtik routerboard that really don't suck, they support VLAN's as does VyOS stuff which is dirt cheap.
FYI I have a Juniper SSG then I got on eBay for less than $100, that is $1000+ high end firewall. I have VLAN's for guest, Internet, home automation stuff, VoIP phones and Asterisk server, camera's and a few test networks. My work network uses a Fortinet in VPN client mode that is yet another VLAN.
Seems you know a bit about VoIP. A few people have made the Skyking connection but FYI I am the same Skyking that was a founding (if there is such a thing, Rob Thomas is the actual Father of FreePBX) member of the FreePBX team, the most popular open source based PBX in the world. My other vocation is Director of Network Engineering at Sangoma Technologies, the company that now owns Digium, the folks that develop Asterisk, an Open Source softswitch that is the heart of FreePBX and untold millions of IVR's and call center systems around the world. VoIP is my other great passion.
