I got it fixed, I contacted my hosting service and they fixed it, they replied me following
“Thank you for holding. This type of issue is usually due to PHP settings being too low. I’ve added a php.ini file and used it to increase the PHP settings. This should prevent the error from occurring again. I apologize for any inconvenience this has caused. ”
Now, i did not get any “Connection Lost” issue while writing and editing blog post in WordPress admin panel.