USB limitations when using external CAN controller

We have run into a problem on the Beaglebone Black (BBB) that I think is due to the implementation of the USB controller and I am hoping to find some advice here. We are running Debian 8 with kernel 4.1. We would like to run a large number of CAN channels (16) from the BBB. We have a 16 channel CAN controller which connects to the BBB via USB. We can successfully bring up an activate 10 of the 16 CAN channels but that appears to be a hard limit. This problem is BBB specific. I have tried a different ARM board ( a small PC/104 board with a 400 MHz processor), a NUC, etc. and only the BBB shows this issue. This must, I believe, be a limitation of the USB implementation. Any help, pointers, suggestions are greatly appreciated!
Thanks, Michael