Tom,
The provider can change the DSL's IP number whenever they want to. In addition, a small thing like a power
outage will also change the IP number. However, it is not necessary to pay for a fixed IP number, just use the
dynamic DNS system built into the RRC instead, it costs nothing.
You have only one external IP number. This means that is is also unnecessary to have multiple devices talking
to dynamic DNS servers, only one is necessary. Placing it in the router or RRC makes no difference, except that
the RRC will only update at the interval you set (minimum 10 minutes), whereas the router will immediately
send its new IP number as soon as a new one is given by the DSL provider.
Assuming you bound the RRC's internal IP number within the router, then the router should not be a problem in
your case. Generally, placing a device within the DMZ does this, but not always. It is always good to double check.
This is the only way to make sure that the RRC always receives the same internal IP number from the router's
DHCP server.
Had I sent you my networking checklist previously, this would have helped prevent this problem, since it goes into
detail on why you must use a dynamic DNS server. If you still want the list, drop me a mail at dj0qn (at) darc.de and
I will send it to you.
73,
Mitch DJ0QN / K7DX