Issues accessing my AWS EC2 Issue

Q1: My Auto-assigned IP address is constantly changing, which means i need to change my access URL every day.

Is the EC2 instance being stopped and restarted daily? If it is then this is expected behaviour https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-instance-addressing.html#concepts-public-addresses

• We release your instance's public IP address when it is stopped, hibernated, or terminated. Your stopped or hibernated instance receives a new public IP address when it is started.

Is there a way to have the same public IP address?

You can bring your own IP (BYOIP) from an address range that you own https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-byoip.html

Or you can allocate an Elastic IP address to the EC2 instance, which will stay the same over time https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/elastic-ip-addresses-eip.html#eip-basics

However, note that the elastic IP incurs a charge during times that your EC2 instance is not running. If your instance is regularly offline (and the fact that its public IP is changing daily suggests that this might be happening) then this needs to be taken into consideration.

More on elastic IP pricing is here https://repost.aws/knowledge-center/elastic-ip-charges

Another option is putting a load balancer in front of the EC2. This would, in effect, allow the EC2 instance to be accessed using the same IP address. The load-balancer will need to be always-on (and thus accruing a charge) for this to be useful.

Q2: Is it possible to use self signed certificates in IIS for access using https to my EC2 instance

Certainly can, no restriction on that. In this regard you can consider the EC2 to be like any other Windows host running IIS.