Send / Receive failed on T-Mobile Netherlands

[JFC]

After a 2 week break I continued testing Dash. But now I 'm not able to send or receive data anymore.
Testing with REPL gives the following results:
Cloud Status: Registrered
Cloud Signal: 99
Cloud Version: 0.10.3
Cloud imei: Not available
Cloud operator: Not available
Cloud Location: Not available
Cloud Send “Hello Hologram” REPL_MESSAGE: Sending message… Failed

My Dashboard log shows: Socket error: timed out
What can cause this problem?

[JFC]

Problem appears to be the signal strength (no signal at all) during a period of time.
A short script reports every second the signal strength:

99, 99, 99, 99, 99, 99, 14, 14, 99, 14,
13, 14, 14, 14, 14, 14, 14, 14, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,

It seems to be stable now.