Info on doing things in Azure.
Rule Processing Summary:
- Outbound - First match wins
- Network rules in order of priority (low to high)
- Application rules in order of priority (low to high)
- Inbound - First match wins
- DNAT rules in order of priority
- Match also allows the traffic.
Site to Site VPN
The above is the article that got it working for me. It was my first route-based VPN and I was missing the crucial info about the weird interface addressing. It's only used for routing and otherwise not needed.