WNDR3400V3 default gateway keeps changing

> [...] my router changing my default address on my pc's side everytime
> it does a dhcp change.

   What does "default address" mean?  The IP address of the network
interface on "my pc"?  Or the default gateway?  Or what?

> I have a static ip set on my pc outside of the range of the dchp but it
> still changes whenever the refresh happens.

   If you have a _static_ address set on your "my pc" (some version of
Windows?), then the router can't affect it.  Do you mean that you've
_reserved_ a (dynamic) address for it on the router?  If so, then what,
exactly is that reservation?  Are you using the right MAC address?
(Determined how?)

   In Windows, a static address is what you specify with "Use the
following IP address".  With "Obtain an IP address automatically",
you're using DHCP, which gives you a dynamic address.  If the DHCP
server has a reserved IP address for a particular MAC address, then your
dynamic IP address will be fixed, even if it's not actually "static".

> [...] I don't see an option to include default gateway with the dhcp.

   If you're talking to the router's DHCP server, then it should always
say that its own address is your default gateway.  (What else would it
say?)

   As usual, showing actual actions with their actual results (error
messages, ...) can be more helpful than vague descriptions or
interpretations.  Copy+paste is your friend.

> My router is the WNDR3400v3

   Firmware version?  (Not really a "Cable Modems & Routers" item, more
of a plain-old router.)