Well, it has been a good week. I figured out the router issue as well.
First, Microsoft has a Network Monitor tool and it is pretty cool. Works fine with Windows 8. You can sniff/monitor network traffic/conversations of individual programs/processes, .etc...

In my case, it didn't care help, but I did see where timeouts occurs, which seemed to be right after a ftp command to LIST / to the MRX-10.
In old router case, the mrx--10 comes back right away: "Directory List" then an OK.

In new router, case, after the ftp LIST /, the mrx-10 responds with some tcp packet and then the following flow 4 times:
a ftp mkd command from server , a tcp packet back from mrx-10
and then a timeout.

I happen to go into network connections on server/windows-8 system and enabled 'sharing' for the connection.
Now downloads work.

It was not clear from network packets, but it worked.
I am guessing the new router (even thru dhcp settings, address ranges, ...) are same as old. Windows treated it as new network. In my case, Network 8, sharing setting was different than old and broke accelerator.

Perhaps this will help others down the road