ODBC Hangs on external data request

I am accessing data on an IBM AS/400, from both Win/98 and NT. I have it working on the LAN. When I go to our remote warehouse I get strange results. I have set up a DSN to access an AS/400 file using MS Excel and MS Query. I request 3 fields from the file. The query returns around 16 to 17 thousand records. When I try it on the WAN it hangs at retreiving data until I click on the spreadsheet and it seems to refresh the data. At that point the spreadsheet fills quickly and the data looksOK. The warehouse is connected using two Cisco 1004 routers and an ISDN line. I even tried taking my notebook to the warehouse, same results. It works on the subnet where the AS/400 is but hangs when on the other side of the routers.