Could you try if the issues you reported are solved by the new bug fix #00 applied to Zeroshell 3.8.1?
i made some test and it seems that the slow conection comes from a bug that i had before in zeroshell.
The BOND only uses 10Mbit on each of my two lines in “Load Balancing and Failover” mode.
If i switch to “Weighted Load Balancing and Failover” with same weight for both lines it uses both with 10Mbit for the download. But the Upload only goes over one of the two lines randomly but with the full bandwidth (32Mbit -4Mbit loss due to overhead as normal).
hope you can help fixing it 🙂