Shadoko,
(I have read many of your prior posts. Your understanding and explanations of what you understand have been very good.)
The 'are you still there' handshakes follow roughly an hour after the last contact, or contact attempt, from the ground to the plane. You are correct that the 17:07UT (probably the ACARS report to RR) would have set the 1 hour timer. Then the 18:03 and 18:05 attempts to send a text message to the flight crew would have reset the 1 hour timer. The SDU (satcom, satellite modem, ...) reset at 18:25 and the following activity through 18:28 would have rest the timer again. Then, the vice phone call attempt at 18:39 to 18:40:56.354 would have been the last timer reset leading up to the 19:41 handshake and the next three (20:41, 21:41, and 22:41).
Then, the next voice phone call attempt (23:13-23:15) reset the timer.
At 00:11 (00:10:58.000), the are-you-there handshake seems to be a little early. I have no explanation for that...
Just to complete the walk through the handshakes...
the SDU restarted (again) at 00:19. Only the initial log-in was completed.
The ground station then checks on the plane at 01:15:56.
(not exactly an hour... But, I have a theory on this one... Possibly the 00:11 log-in had not completed far enough to terminate the prior connection established at the prior log-in (18:25-28). The last contact from that communications session was the voice call attempt that ended at 23:15. ...and that would be an hour.
the ground station retries the are-you-there message few times (01:16:06 and 01:16:15), since the one at 01:15 was not answered.