T2 Unlimited Instance Failing to Load Jenkins

There could be several reasons for this. Here are a few possibilities:

• Insufficient Memory: Jenkins can be resource-intensive, especially with large builds or a high number of builds. If your instance doesn't have sufficient memory, it could slow down or become inaccessible.

• Disk I/O Bottleneck: If you're performing operations that require a high rate of disk I/O, it could cause performance issues.

• Network Bandwidth: Limited network bandwidth can also cause accessibility issues.

Here's how you could troubleshoot these issues:

• Monitor CPU Utilization: You can monitor your instance's CPU utilization through Amazon CloudWatch. If it's consistently high, you might need a larger instance type.

• Monitor Memory Usage: Unfortunately, AWS does not provide memory usage metrics out of the box. However, you can set up custom metrics to monitor memory usage.

• Monitor Disk I/O: You can monitor Disk I/O through Amazon CloudWatch. If Disk I/O is high, consider an instance type with a higher I/O performance or optimize your disk operations.

• Monitor Network Bandwidth: You can monitor Network Bandwidth usage through Amazon CloudWatch. If Network Bandwidth usage is high, consider an instance type with higher network performance.

One additional recommendation would be moving to a new family, which usually comes with better performance for the same price, but a lot of people still use t2 because of the free tier.

If none of these steps resolve the issue, it might be worth contacting AWS Support for further assistance.