After upgrade to Version v4.7.2 beta the range for port forwarding works!
But just two hints completly independent from this topic:
Upgrade with "keep settings" option doeas not work. A second attempt without the "keep settings" was necessary.
With new Version v4.7.2 luci webinterface at port 8080 is not able to login. Only luci webinterface at port 8443 is able to login. In both cases appears a "luci: accpeted login on / for root from....
May I know did the router modify the "http" port of uhttpd in the previous firmware?
Please try upgrading without "keep settings", or resetting firmware in the current version.
After v4.7.x, Luci is listened to by uhttpd, probaly something previous configurations impact the "http" port configuration.