I understand why there are issues with Annex M deployements in UK, however I believe the Annex A should be compatable.
In every case teh router is either doesn't sync or is unstable and collapse after a certain period depenedent on the amount of data.
The problem is characterised by middle and big buffer failures. ICMP and SSH to the box are fine, but normal data traffic stops.
A reboot is the only option to clear the buffers
Here is example info:-