Set up a DFL-210 to replace the old DIR-615.
After many calls to DLink support, make it work.
However, I find out internal host can not talk to internal DNS server.
Let us say:  Internal DNS server is 172.16.100.195 running powerDNS.  
My internal host is:  172.16.100.234, which is a Linux.
My login to Linux is extremely slow.  Also see bunch of error from internal DNS server.
Not sure where the issue is.
Please help.
Thanks.