Here is my configuration for the mirror…
I am running SBC on a Win2k8 R2 machine (where the RTM will be installed some day)

I will post the wireshark dump later on… lastnight around 2am i had another idea what could be a possible cause of the problem…

i am running the SBC server dualhomed. I have 1 internal network card (static; which i have chosen to use for services at setup) and 1 network card (dhcp) for the connection to internet.

i will do another fresh install from SBC but ill remove the second networkcard and i will use the proxy that i installed for the connection now…
if this fails then i will post the logs from wireshark (which i have to dump again then)

since ill be in meeting in the afternoon (all afternoon) it might be later tonight i will post the dump…

edit:
i did the setup several times this morning cuz of problems with files on the downloadserver side according to the (deleted)log.
i noticed that there have been different mirror sizes:
i have seen 154MB and 160MB.
Right now im downloading a mirror size 154MB.

Assuming those sizes and file errors are from updates done by Avast.