"Just add two "sites" to the app, you say?"
Never been problem for me
In my router, I set up a DNS entry for the DVR. So I forward mydvr.dydns.org to 192.168.1.98, for example. It works fine, but there's one caveat: it's going to send all traffic to that one address on the LAN. So if you have more than one DVR, or a DVR and a PC, for example, with different external ports forwarded to each, you won't be able to reach all of them from inside the LAN.
This isn't a problem for me because it's the only device I reach via dyndns, anyway, but could be for some. You could get around it by making a new dynamic dns host, but that's a bit clunky.
...when at home, the DDNS site errors and when at Starbucks the local site errors...
Why does the DDNS site error at home?
I did setup few times 2 entries on customer ph
1.local (Home or office)
and explain when to use it
IPVMU Certified | 02/09/16 06:13am
Supply your own router as part of the install?
If the ISP has a combo modem/router set it to bridge mode. Ubiquiti Edgerouter for $59 can do NAT hairpinning or custom DNS entries for internal clients.
Do you have a DLINK router, or one where you can enable independent endpoints, like so:
IPVMU Certified | 02/09/16 01:19pm
Bob and Ethan's solutions are the correct ones. This is a limitation of the router, it's not a problem with the DVR. Whatever you use to resolve DNS entries internally on the network, if you're able to, you need to set a static A record that essentially says something like:
DVR.mydns.org -> 192.168.1.200
Then set your app to look to DVR.mydns.org. When you are inside the network, the internal DNS service (whether it be an internal DNS server or on the router), should override what the outside DDNS service says and should point you to the correct IP address on the inside. When you are outside the network, the DDNS service should point you to the appropriate public IP address.
We don't use DDNS as we have static IP addresses and our own domain name server, so I make the entries on our internal DNS server for inside name to IP resolution and our domain name registrar's (ie GoDaddy, Network Solutions, Register.com, etc) DNS server for outside name resolution so I only have to make one DNS address entry.
If your customer doesn't have sophisticated enough systems to do that, they'll just have to upgrade. Partner with an IT company if you don't know how, because it can be a mess to setup if you don't know what you are doing.
Comprehensive list of common routers, whether they support NAT loopback by default, and how to make them when they don't.
Well I see Luis and U3 beat me to the answer: it's a limitation of the router, and the only sure way around it, if the router doesn't have the option, is to replace the router with a suitable one.
Well, not necessarily "replace"... there may be other possibilities, depending on the setup. My home network uses a cable modem operating as a standard gateway, and a router with DD-WRT firmware as my primary "control" unit. The cable modem provides a separated guest network and unfettered connection for my son (he's a gamer, ping time is god), while the router handles all the DHCP, firewall, PXE control, etc. for all other "mission control" operations :) The cable modem itself doesn't support loopback, but when my internal router's WAN IP is set as a DMZ, that doesn't seem to matter.
If it's a supported router, you could always look at flashing a custom firmware, such as DD-WRT, OpenWRT, Tomato, etc. I can't speak for the others, but DD-WRT will do NAT loopback with a short firewall rule (copy-and-paste from their wiki).
Fortunately, if you do end up having to replace the router, this isn't a function that's limited to the expensive high-end models - as I noted to Ethan above, it's not something overly advanced or esoteric, it's just uncommon because the need for it has traditionally been uncommon. But as U3's link shows, it is available in a number of lower-cost routers.