If your up.time Data Collector service will not start, check the uptime.log file for an error similar to:

xxx.xxx.xxx.xxx: is not a trusted ip
xxx:xxx:000:xxx:xxx:0X0x:x000: is not a trusted ip

This is usually caused by a change in the uptime.conf file related to the trustedIpAddresses variable. If changes have been made to this parameter, it is advisable to revert back so it reads as follows:

trustedIpAddresses=0.0.0.0/0


Once this change has been made, restart the data collector: 

Unix: # /etc/init.d/uptime_core start
Windows: > net start "up.time data collector"

For future reference bookmark - Starting (or restarting) and Stopping Uptime Infrastructure Monitor