R6220 - How do I get the router to pass DNS Server address/addresses to wireless connected devices?

> [...] The router is currently passing it's wireless ip-address [...]

   That's its LAN IP address ("192.168.1.1"?).  It's true for wired or
wireless.

> [...] as DNS server to connected devices.

   That's what it does.

> Unfortunately I am unable to resolve dns requests using the routers
> wireless ip-address/gateway address. [...]

   What happens when you try?  "unable" is not a useful problem
description.  It does not say what you did.  It does not say what
happened when you did it.  As usual, showing actual actions (commands)
with their actual results (error messages, LED indicators, ...) can be
more helpful than vague descriptions or interpretations.

   What are the DNS servers specified in the configuration of the R6220?
BASIC > Intenet : Domain Name Server (DNS) Address : ...

> [...] If I manually configure isp dns server addresses [...]

   "manually configure" them _where_?  On the R6220, or on your client
device, or where?

> [...] Is there a way to have the router pass ISP DNS server addresses
> to connected devices?

   Do you mean, can you specify which DNS server(s) the DHCP server on
the R6220 will pass to its DHCP client devices?  I'd say, no.  I've
never seen any user-specified options for the DHCP server on any of
these routers, other than Address Reservation.