Admin page does not load if kept idle for sometime

Observing an issue where F5 admin UI page does not load after a certain period of time. At this time, i am able to access the console(not SSH - as SSH also does not work) from my vCenter UI and even the VIP is accessible. The only workaround at this time is reboot the appliance and it starts working.

This is just small setup which i have it in my lab with just one NIC - not much traffic.

Could you please help me where to look for the error and what is causing the problem ?