FB7340: can't use TC shaping on DSL interface

[DualIP]

First of all, on FB7170, I got upload traffic shaping working like a charm.
Instead of Fritzbox GUI or ar7.cfg, i used the patch from
http://www.jzab.de/content/customize-your-fritzbox-allow-traffic-shaping
I used TC commands to create multiple classes and classify packets on the dsl interface


Now I tried to do same trick on FB7340 but ran into a problem:
I can't slow down dsl interface anymore!
All modules load fine, classification works, I see traffic ending up in different classes, but no bandwidth limiting and packet drops. (excess low prio traffic should be dropped!)

All stuff in kernel seems to be present, the classic command to slowdown an interface works ok on both LAN interface and ADSL interface, but not on DSL interface:

tc qdisc add dev dsl root tbf rate 220kbit latency 50ms burst 1540

(I'm not able to use shaping on adsl interface: can't classify packets because of weird ptp encapsulation used)

Hints welcome...

 

[DualIP]

Although both tcpdump and wireshark don't understand packets on adsl interface (bogus ip header length), tc filter commands work fine on adsl interface, and I moved shaping stuff to that interface
One caveat: On adsl interface, packets are NATted to outside address, so private source address are no longer available to prioritize internal hosts