AWS Instance Not Reachable with Ubuntu Desktop

I'm here to ask a a question about a software tool commonly used by programmers: AWS.

I need to run a cluster that processes jobs which require a desktop GUI. One of the issues I'm running into is after some period of time (<12 hours), the instance becomes entirely unreachable via (SSH/HTTP/RDP), I see this in the AWS console. I've attempted to take instance screenshots using the AWS console, but those also fail.

• If I restart the instance, everything works just fine
• I've tried this with MATE and Ubuntu desktop, the same thing happens
• On MATE desktop, I took a screenshot under "Monitor and troubleshoot" in AWS Console
• This showed a login screen which prompted me to disable automatic logout using the settings UI, but the instance was still unreachable
• I assumed I didn't properly disable automatic logout on MATE, so I switched to Ubuntu desktop where doing so was straight forward.
• When using Ubuntu desktop, the instance becomes unreachable and then won't restart: I need to force stop the instance

Details about the VM:

• AMI: ubuntu/images/hvm-ssd-gp3/ubuntu-noble-24.04-amd64-server-20240701.1
• Instance Type: g4dn.xlarge
• Appropriate ports are all open for inbound and outbound connection (I can connect until the machine is idle for some time)
• Autologout is disabled

Here is the script I use to set up the instance. Not I'm aware there's a spelling error blcklist: I had to change it to get around AWS forum's censor:

echo "=== Updating package lists"
export NEEDRESTART_SUSPEND=1
sudo apt update

echo "=== Installing AWS CLI"
sudo snap install aws-cli --classic

echo "=== Installing GPU drivers"
sudo apt install ubuntu-drivers-common
sudo ubuntu-drivers install nvidia:535

echo 'blcklist vga16fb' | sudo tee -a /etc/modprobe.d/blcklist.conf
echo 'blcklist nouveau' | sudo tee -a /etc/modprobe.d/blcklist.conf
echo 'blcklist rivafb' | sudo tee -a /etc/modprobe.d/blcklist.conf
echo 'blcklist nvidiafb' | sudo tee -a /etc/modprobe.d/blcklist.conf
echo 'blcklist rivatv' | sudo tee -a /etc/modprobe.d/blcklist.conf

echo "=== Installing desktop and RDP"
sudo apt install -y ubuntu-desktop xrdp
echo "gnome-session" > ~/.xsession
sudo adduser xrdp ssl-cert
sudo ufw allow 3389/tcp

echo "=== Upgrading the system"
sudo apt upgrade -y

echo "=== Rebooting the system"
sudo reboot