nslookup failed - Got SERVFAIL reply from 172.26.0.2

Based on the information provided, it appears that your Lightsail instance is having trouble resolving the hostname using its default DNS server (172.26.0.2), while external DNS servers like Google's (8.8.8.8) can resolve it correctly. This suggests a potential issue with the DNS configuration on your Lightsail instance or within your VPC.

Here are a few steps you can take to troubleshoot and potentially resolve this issue:

1. Check the /etc/resolv.conf file on your Lightsail instance to verify the configured DNS servers. If the file is pointing to an incorrect or unresponsive DNS server, you may need to update it.

2. Ensure that your Lightsail instance's security group or firewall settings allow outbound DNS traffic (usually on port 53).

3. Verify that the DNS records for your domain are correctly set up in your DNS management system (e.g., Route 53 or Lightsail's DNS zone).

4. If you're using a custom domain, make sure the nameservers are correctly configured with your domain registrar.

5. Try updating the instance's DNS configuration to use public DNS servers temporarily (like 8.8.8.8) to see if that resolves the issue.

6. If the problem persists, you may want to create a snapshot of your instance and launch a new instance from that snapshot to see if the issue is related to the specific instance configuration.

If none of these steps resolve the issue, it may be worth contacting AWS support for further assistance, as there could be an underlying network or configuration problem within your Lightsail environment.

Sources
DNS Doesn't resolve | AWS re:Post
AWS Lightsail help | AWS re:Post
Troubleshoot website access errors on Lightsail | AWS re:Post

Thank you, I'll look further into the DNS side of things. Cheers