AWS EC2实例在部分网络出现ERR_CONNECTION_RESET问题技术问询

Alright, let's tackle this specific issue where one regional user can't load your Airbnb-style property listings (getting net::ERR_CONNECTION_RESET) while everyone else—including you and testers across multiple locations—has no problems. Since clearing Chrome cache didn't help, we can rule out basic client-side caching and focus on targeted network or configuration culprits.

1. Start with AWS-Side Regional Restrictions #

First, check if your EC2 setup is accidentally blocking traffic from this user's region/IP:

• Security Groups & NACLs: Head to the AWS EC2 console and review your instance's security group inbound rules. Look for any IP range restrictions that might exclude the user's region. Don't forget VPC Network ACLs too—they're stateless, so both inbound and outbound rules need to allow traffic for connections to work. It's easy to accidentally add a geofilter or a deny rule that catches this specific user's IP.
• CloudFront/AWS Shield (if used): If you're using CloudFront as a CDN or AWS Shield for DDoS protection, check their dashboards for any regional blocks or heuristic filters that might be flagging the user's traffic as malicious. Legitimate traffic can sometimes get caught in these filters, especially if the user's ISP has a history of suspicious activity.

2. Diagnose the User's Network Path #

The error suggests the connection is being dropped mid-flow, so let's map the user's route to your EC2 instance:

• Run traceroute/mtr: Ask the user to open their terminal (Mac/Linux) or Command Prompt (Windows) and run:

  traceroute your-ec2-public-ip-or-domain
  

  For more detailed, real-time data, have them use mtr:

  mtr your-ec2-public-ip-or-domain
  

  This will show exactly where the connection fails—if it drops at a specific ISP hop or regional gateway, that's an ISP-level routing/block issue.
• Test alternate networks: Have them try accessing the service via mobile data instead of their home/work WiFi. If it works, the problem is with their local network's firewall or router blocking your EC2 instance's port.
• Disable VPN/proxy: If the user uses a VPN or proxy, ask them to turn it off and retry. VPNs often route traffic through regions that your security rules might block.

3. Check EC2 Instance-Side Logs & Metrics #

Even if most users work, there could be a targeted issue with this user's traffic:

• Review application logs: Check your web server logs (Nginx/Apache) and backend app logs to see if the user's requests are even reaching the EC2 instance. If there are no entries for their IP, the connection is being dropped before hitting your app.
• Verify port availability: Make sure the port your backend uses (e.g., 80, 443, or a custom port) is listening on the EC2 instance. Run this command on the instance:

  netstat -tulpn | grep LISTEN
  

• CloudWatch metrics: Check EC2 Network metrics (Packets Out, Dropped Packets) in CloudWatch. If you see a spike in dropped packets when the user tries to connect, that points to a network interface issue or AWS-level throttling for their IP.

4. Client-Side Checks Beyond Cache #

Since clearing cache didn't help, try these deeper client fixes:

• Reset Chrome network settings: Have the user go to Chrome Settings > Advanced > Reset and clean up > Restore settings to their original defaults. This resets proxy settings, cookies, and network configs without deleting bookmarks.
• Test other browsers: Ask them to try Firefox, Safari, or Edge. If it works elsewhere, a Chrome-specific extension (like an overzealous ad blocker or firewall tool) is likely blocking the connection.
• Temporarily disable antivirus/firewall: Local security tools sometimes block connections to specific IPs/ports. Have them disable these temporarily (with caution) to see if the connection goes through.

Last Resort: VPC Flow Logs #

If you still can't find the root cause, enable VPC Flow Logs for your EC2 instance's subnet. These logs will capture every packet going to/from the instance, showing exactly whether the user's traffic is being allowed or denied at the VPC level.

内容的提问来源于stack exchange，提问作者user9148237