The HTTP URL you use with DateAndTime DOES have to be reachable from the devices.  But that URL does NOT need to be the MSP Server, although it CAN be.  The URL just needs to be some HTTP Server that is reachable from the device and that knows the correct time (or at least that you trust the time of).  In most cases, it would be better in a situation where MSP is inside a firewall to have devices contact some other HTTP Server to get the time.  Or use the SNTP protocol to access some time server.

Pablo, The MSP server sits inside the corporate network while the relay server sits outside. The devices never need to access the MSP server directly. They only need to access the relay server, as does the MSP server, via FTP. I have a client with hundreds of field devices working in this way. If you have any questions let me know. Thanks, Damian

i used the package dateandtime to synchronize the the time of the devices and i remember i had to put the webpage address of the msp to make it work. this could be  a problem?