Well I figured it out, it's a problem with my MX85.  I did all kinds of things over the weekend like put the MX85 on a different subnet, plugged into different internal switches, etc. to no avail.     I took another MX64 and set it up on the Work side with exactly the same settings as the MX85, just one IP address away, and updated my internal static route to it.  My head end config is very simple, passthrough VPN concentrator, site to site hub with one /16 subnet and that's it.     The MX64 works great, I'm getting 20-40mbps VPN file copying.  I can point the remote MXs back to the MX85 and change the static route back and get the slow copying again.  I did a packet capture on a file transfer to the MX64 and it looks "clean" whereas the packet capture to the MX85 is full of out of order packets and retransmits.     I did notice my MX64s are all on firmware 15.44 and the MX85 is showing 16.8, I guess this is because it's a brand new device?  I wonder if its a hardware bug or software bug?  I'm about to get back on the phone with support and show them these findings.       EDIT:  Just got off the phone with support.  We upgraded the MX85 from 16.8 that it shipped with to release candidate 16.15 and the problem is fixed.  ... View more