Comfort does have an accurate real-time clock and calendar which is normally accurate to within 4 to 10 minutes per month. However the time is reset to a default time whenever the system completely loses its power and battery backup. For a working installation, there is a back-up battery which ensures that the system time is maintained until a flat battery situation.
For those without the ETH03 time synchronisation feature, the Comfort Time can be adjusted by a value in seconds to correct any time inaccuracy
Go to Configuration > Modules and Settings > Time Adjust as shown below
Enter a value of - 60 to +60 seconds in the field to make a daily adjustment to the time. First you will need to determine approximately how many seconds fast or slow the Comfort Time is every day. For example if the Comfort time is fast by 10 seconds every day, enter -10 into the field to slow down the time by 10 seconds a day
If the time is 10 seconds slow every day, then enter +10 to speed up the clock by 10 seconds per day