Port forwarding Port 53 or IP passthrough to synology DS214play

I am in a bit of a pickle with the Motorola NVG589.  I am setting up my Synology DS214play with DNS server so I can use a public domain name that will manage my Web Server, Mail Server etc.  The instructions for the DNS Server setup advises Port 53 be forwarded to my NAS Server.  When I click a

dd for the port forward I receive this error message

"Warning: The change you are attempting to make may cause AT&T U-verse TV to stop working properly."

Now I need to know whic is the better to choice A. to go ahead and forward the port or B. do the IP pass through.

If I chose IP Passthrough then I need to know which option within PassThrough Mode:  1.  DHCP Dynamic 2. DHCP -S Fixed or 3. Manual

If I choose to ignore the warning and go with Port forwrding what could be the issue down the road and which is the better option?

I am leaning towards IP PassThrough.