feat(srv): add troubleshooting pages MTA-5446 (#5280)

* feat(srv): add troubleshooting pages MTA-5446

* Apply suggestion from @RoRoJ

Co-authored-by: Rowena Jones <[email protected]>

* Apply suggestions from code review

Co-authored-by: Rowena Jones <[email protected]>

* docs(srv): update

---------

Co-authored-by: Rowena Jones <[email protected]>

Author: SamyOubouaziz

pages/serverless-containers/troubleshooting/cannot-access-container.mdx

@@ -0,0 +1,38 @@
+---
+title: I cannot access my container
+description: Troubleshoot issues encountered while accessing or connecting to your Scaleway Serverless Containers.
+tags: serverless containers troubleshooting issue error state unreachable connection log in access
+dates:
+  validation: 2025-07-15
+  posted: 2025-07-15
+categories:
+  - serverless
+---
+
+## Problem
+
+I am experiencing issues while accessing my Serverless Containers.
+
+## Possible causes
+	
+- The container returns a DNS error or issue
+- The container response time is abnormally long
+- The container returns a `HTTP 5xx` error
+- The container returns a `Could not resolve host` error
+- The container is in an error state
+
+## Solutions
+
+- If you encounter a DNS issue, refer to the [dedicated troubleshooting page](/serverless-containers/troubleshooting/known-dns-containers-errors/).
+
+- For long response time, check:
+    - if the first instance of the container is currently starting. This can entail a [cold start](/serverless-containers/concepts/#cold-start)
+    - if not, [check the metrics in Cockpit](/serverless-containers/how-to/monitor-container/) (especially CPU) and see if there is a high usage explaining the slow response
+
+- `HTTP 5XX` errors can come from the application itself. Check if you can reproduce locally with a dummy container, or if your application is misbehaving. 
+
+- A `Could not resolve host` error can indicate that you are trying to reach the container in IPv4 with its IPv6 address, or vice versa. This can also appear if there is a [DNS issue](/serverless-containers/troubleshooting/known-dns-containers-errors/).
+
+- If your container is in an `error` state:
+    - Refer to the [dedicated troubleshooting page](/serverless-containers/troubleshooting/container-error-state/).
+    - Check the `error_message` field in your [Cockpit logs](/serverless-containers/how-to/monitor-container/) to investigate the actual cause.

pages/serverless-containers/troubleshooting/index.mdx

@@ -68,4 +68,6 @@ productIcon: ContainersProductIcon
   - [My container stopped working after a redeploy](/serverless-containers/troubleshooting/container-stopped-after-redeploy)
   - [Tests fail on Serverless Containers](/serverless-containers/troubleshooting/tests-fail-on-container)
   - [I am experiencing clock drift with my Serverless Containers](/serverless-containers/troubleshooting/container-clock-drift)
+  - [I am experiencing DNS issues with my container](/serverless-containers/troubleshooting/known-dns-containers-errors/)
+  - [I cannot access my container](/serverless-containers/troubleshooting/cannot-access-container/)
 </LinksList>

pages/serverless-containers/troubleshooting/known-dns-containers-errors.mdx

@@ -0,0 +1,41 @@
+---
+title: I am experiencing DNS issues with my container
+description: Troubleshoot Domain Name System (DNS) issues with Scaleway Serverless Containers.
+tags: serverless containers troubleshooting issue error state dns domain name system
+dates:
+  validation: 2025-07-15
+  posted: 2025-07-15
+categories:
+  - serverless
+---
+
+## Problem
+
+I am encountering DNS errors while using Scaleway Serverless Containers.
+
+## Possible causes
+	
+The DNS record for the default endpoint (`functions.fnc.<region>.scw.cloud`) is not available yet on every DNS resolver. This issue can appear even a few seconds after the container is marked as “ready”, and mostly appears when the user calls the container too early after the first deployment.
+
+- For custom domains, a DNS resolution failure can indicate that the custom domain is not properly configured.
+
+
+## Solutions
+
+- When the DNS answer is cached locally, you can:
+  - retry later (negative DNS caching lasts around 60 seconds)
+  - try from another host, where the DNS answer is not cached
+  - clean the DNS cache locally
+  - use another DNS resolver (common DNS resolvers should have the record in a few seconds)
+
+- For custom domains:
+  - check the configuration on your DNS provider
+  - check the TTL on the DNS record. High TTL values will cache the DNS answers for a long time, so we recommend adding a small TTL for setting up the custom domain (60s)
+  - make sure [you properly configured your custom domain](/serverless-containers/how-to/add-a-custom-domain-to-a-container/) in Serverless Containers
+
+
+## Going further
+
+- Refer to the dedicated documentation on [how to add a custom domain to a container](/serverless-containers/how-to/add-a-custom-domain-to-a-container/) for more information.
+
+- If you manage your domain names with Scaleway, refer to the [Scaleway Domains and DNS documentation](/domains-and-dns/).