I have nearly the same problem. I have a free DynDNS Service from a other provider in Germany. But my RV320 supports NO other DynDNS Provider as DynDNS.org or 3322.org.
Cisco is a company with a lot of customer and with high cost products. But all SmallBusiness Router products didn't support customer spec. settings. Cheap Router in low cost sector brings a hand full DynDNS out of the box in list menu and a "other provider" setting. Poor Cisco.
I kick my cisco product(s) [RV220W] in the dustbin and buy low cost products, that I'm flexible of new services, as with expensive Cisco products.
If you search in the support database, many, many people have the same problem and open a support ticket.
A new Firmware can fix this problem. But Cisco takes not care about the issues / problems / request of they customerer.
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