APIM stv2.1 experience multiple client connection failures since yesterdays update

All resolved now thank you. we found the container apps were stuck in a startup loop due to health probes that a apim restart surfaced

Hi @Declan O Malley ,

Check below steps:

1. Developer SKU is a single-instance, no-SLA tier
   • During platform/OS patching or global upgrades, the lone role instance can go offline or be slower to respond. Upgrades can sometimes take many hours. For production workloads, Microsoft recommends Standard/S1+ (2+ instances with built-in LB).
2. New VIP and control-plane endpoints on stv2.1
   • The stv2 upgrade changes the VIPs your instance uses. If you’re resolving the backend service using DNS, ensure it’s not caching the old VIP.
   • Management/control-plane traffic still arrives on port 3443. If you have forced-tunneling or UDRs, you must allow the Azure APIManagement service tag or specific RP IPs back to the internet so replies can return.
3. VNet integration and NSG/UDR considerations
   • Verify your APIM subnet’s NSG allows outbound traffic to your App Container Environment on the required ports.
   • Make sure you’ve enabled service endpoints for any Azure PaaS back ends (Storage, SQL, Key Vault, Event Hubs).
   • If you’ve forced all internet-bound traffic through a firewall, add UDRs for the control-plane IPs (see table below) with next hop = Internet so management traffic can complete symmetrically.
4. Diagnostics and monitoring
   • Turn on request tracing or diagnostic logs in APIM to see whether these are timeouts or HTTP errors coming from the gateway vs. your backend.
   • Check Azure Resource Health to see if there are known upgrade events. Note: Developer SKU may not always emit health alerts.

Next steps you can try right away:

• Scale out or upgrade to a higher SKU (Basic/Standard) if you need production-grade availability.
• Review your NSG and UDR configs for both control-plane (3443) and your backend ports.
• Flush any stale DNS entries for your backend hostnames.
• Enable APIM diagnostic logs and look for patterns in the failure codes.

References:

• Service is down or outage: https://learn.microsoft.com/azure/api-management/availability-outage
• API Management VNet common network config issues: https://learn.microsoft.com/azure/api-management/api-management-using-with-vnet?tabs=stv2#-common-network-configuration-issues
• Control-plane IPs & UDR guidance: https://learn.microsoft.com/azure/api-management/virtual-network-reference?tabs=stv2#control-plane-ip-addresses
• Create activity log & resource health alerts: https://learn.microsoft.com/azure/service-health/alerts-activity-log-service-notifications-portal

Hope this helps!

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