Azure VPN Gateway’s SSTP Point-to-Site (P2S) connections to private VNETs can cause networking issues in WSL. Symptoms include hanging SSL connections, frozen database clients, and DB clients failing in Docker/Kubernetes networks. I encountered this with a SSL secured MySQL connection which would just hang with nothing informative. Worked fine from the Windows host. The culprit: MTU mismatches. The Problem MTU (Maximum Transmission Unit) is the largest packet size that can be transmitted over a network connection.

A short exploration of options for connecting to resources with private VNETs in Azure. Focused on boutique dev work. Think access to state maintaining services like SQL databases, CosmosDB, Redis etc. Costs are indicative at time of writing. Costs vary between Azure regions. Figures are in AUD, multiply by .6 to get an approximate in USD. I haven’t considered use of Site to Site (S2S) VPNs to connect to existing Point to Site (P2S) VPNs here, if that connectivity is a requirement then these options are likely not relevant.