Since a sudowrt router is not likely to be connected directly to an ISP (it is usually connected through an existing router) it probably does not make sense to run normal NAT-PMP and uPNP, but it should be theoretically possible to not only obey requests from these protocols but also forward those requests to the upstream router and only return success if both the local and upstream router are successful in obeying the request. Probably this is not supported by the existing openwrt packages, but we could implement it.
Since a sudowrt router is not likely to be connected directly to an ISP (it is usually connected through an existing router) it probably does not make sense to run normal NAT-PMP and uPNP, but it should be theoretically possible to not only obey requests from these protocols but also forward those requests to the upstream router and only return success if both the local and upstream router are successful in obeying the request. Probably this is not supported by the existing openwrt packages, but we could implement it.