The device has an internal clock.
The firmware can be set to use the Internet (NTP) but also allows manual setting of the time/date to update the system's internal clock. In that case the Internet time is ignored.
When NTP is used, the device has 3 standard NTP servers that it will use: 0.pool.ntp.org, stdtime.gov.hk, time.stdtime.gov.tw
It will probe the Internet time at various actions, like when you enter clock mode.