Unknown port bridge on L2tp ver3

Hi there..

I had CHR on my vps running hotspot using l2tp ver3 unmanaged mode at other site behind NAT ( no ip publik ) is runninng well also UM5..butt my problem is when remote site disconneted for some reason the port bridge become unknown and i put it back manualy, is there avalaible L2tp ethernet binding ( look like l2tp server binding)..so it will be back automaticaly, very tirred keep stay on my chair to keep not at unknown port. , hope someone have any idea to resolve..
l2tp disconnect.png
l2tp.png

found to resolve… only pick dynamic interface on port bridge…
l2tp ok.png