Server status change from UP to DOWN

Why does FRAS,FIRS,WEBSITE,TODO,CDE, etc server keep changing status from UP,UP... to DOWN,DOWN... (411 page) which prevents me from connecting to store or archive? Is there a part that needs replacing?

crwdns2893858:0crwdne2893858:0 crwdns2893862:0crwdne2893862:0

crwdns2894050:0crwdne2894050:0

crwdns2889612:0crwdne2889612:0 0
crwdns2892346:0crwdne2892346:0