I can't ping my static IP

Hello.

Since name resolution is possible with the "dig" command, I think there is no problem with the domain settings.

dig dwm.io

; <<>> DiG 9.18.18-0ubuntu0.22.04.1-Ubuntu <<>> dwm.io
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3632
;; flags: qr rd ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;dwm.io.                                IN      A

;; ANSWER SECTION:
dwm.io.                 0       IN      A       44.232.172.114

;; Query time: 150 msec
;; SERVER: 172.20.208.1#53(172.20.208.1) (UDP)
;; WHEN: Mon Mar 31 08:42:10 JST 2025
;; MSG SIZE  rcvd: 46

As stated in the automated response from re:Post Agent, I think what you need to check is the security group and firewall settings.
In the case of Lightsail, as described in the following document, ICMP is not allowed by default, so communication will not be possible unless you change the settings.
https://docs.aws.amazon.com/lightsail/latest/userguide/understanding-firewall-and-port-mappings-in-amazon-lightsail.html#default-lightsail-firewall-rules

In the case of EC2, ping will not be successful unless ICMP is allowed in the security group's inbound rules.
Also, if you are accessing a web server, HTTP or HTTPS must be allowed.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/changing-security-group.html

Based on the symptoms you've described, it appears that there might be an issue with your Lightsail instance or its network configuration. Here are some potential causes and steps to troubleshoot:

1. Security Group / Firewall Settings: Check if ICMP (used for ping) is allowed in your instance's security group or firewall settings. You may need to configure your Lightsail firewall to allow ICMP packets.

2. DNS Propagation: If you've recently made changes to your DNS settings, it can take up to 48 hours for these changes to propagate globally. This could explain why the domain resolves to an IP but doesn't respond.

3. Instance Status: Verify that your Lightsail instance is running and healthy. You should be able to check this in the AWS Lightsail console.

4. Web Server Configuration: If you can't access your website, it's possible that your web server (e.g., Apache or Nginx) is not configured correctly or is not running.

5. Network ACLs: If you're using a VPC, check your Network ACLs to ensure they're not blocking incoming traffic.

To troubleshoot:

1. Try accessing your website using the static IP directly in your browser, bypassing DNS.
2. Check your Lightsail instance's firewall settings and ensure ICMP and HTTP/HTTPS (ports 80/443) are allowed.
3. Verify your DNS settings in your domain registrar and Lightsail to ensure they're pointing to the correct static IP.
4. If possible, try to SSH into your instance to check if the web server is running and properly configured.
5. Clear your browser cache and try accessing the site from a different network to rule out local issues.

If these steps don't resolve the issue, you may need to contact AWS support for further assistance, as there could be an underlying problem with the Lightsail infrastructure or your specific instance.
Sources
When I ping my Lightsail static IP, return just once then timeout. So I cannot using my domain name | AWS re:Post
Unable to ping my Ec2 instance using Public Ip | AWS re:Post

It seems like the issue is not just with ICMP (ping), but your website may not be running correctly. The problem doesn’t appear to be related to DNS resolution, as I was able to resolve the IP address, but when I tried to access the site directly via the IP, I encountered a 504 Gateway Timeout error.

A 504 error typically indicates a server-side issue, which often requires action from the web server administrator or hosting provider to resolve. Could you check if the server is properly communicating with the database or if there are any other issues on the backend that might be causing the timeout?

Let me know if you need help troubleshooting further!