Issue All hosted sites start giving Time-out error

[kirtanparmar]

I've hosted 5 Wordpress blog on Plesk panel

This happens randomly to all sites, It's keep giving Timeout error.

To fix it i run below command on server and after Apache restart everything becomes normal

sudo service apache2 restart

I am posting here because i want permanent solution, This is happening every 2-4 days. I have upgraded my server with higher configuration even tho when we don't have more traffics. but still it is keep happening