There is no "danger" in connecting your Vonage adaptor behind another router (whether it is a standalone router or a combination modem/router).
The primary "problem" you might run into is that depending on the available bandwidth and your usage of that bandwidth, you may need to setup some QoS rules to give the Vonage service/device a higher than normal priority when it needs it in order to preserve voice quality during periods of heavy internet usage.
I do not have U-verse service, so I can't offer any specific instructions for setting up QoS in the U-verse 2wire router, but if you should need to setup QoS, you should be able to find someone either in this forum or in the »2Wire
forum to help you.--
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