LED on netdev not working after reconnect (PPP)

[berni@…]

LED trigger on tx/rx on my PPPoE upstream interface does not work after the daily disconnect. Setting the device again fixes it. Probably the kernel is looking for the wrong ifidx.

system.@led[0]=led
system.@led[0].default=0
system.@led[0].sysfs=buffalo:red:diag
system.@led[0].trigger=netdev
system.@led[0].mode=tx rx
system.@led[0].name=PPP
system.@led[0].dev=pppoe-mnet

# broken
root@router:/sys/devices/platform/leds-gpio/leds/buffalo:red:diag# cat trigger 
none timer default-on [netdev] phy0rx phy0tx phy0assoc phy0radio phy0tpt phy1rx phy1tx phy1assoc phy1radio phy1tpt usbdev 
root@router:/sys/devices/platform/leds-gpio/leds/buffalo:red:diag# cat device_name 
pppoe-mnet
# fix to get it working again:
root@router:/sys/devices/platform/leds-gpio/leds/buffalo:red:diag# echo pppoe-mnet > device_name

This is probably a kernel limitation, a possible solution would be to set the trigger again when the interface comes up.