Hi all,
before I take the step and open a bug with MikroTik support, I’d like to get forum feedback as it only concerns a testing setup and may therefore also be an user error. 
If I setup a L2TP link with mtu and mru set to 1452, I can pass packets(icmp ping) over that link with the expected size of 1452bytes, so far so good.
As soon as I set MRRU on both sides to say 1614, I can’t pass packets with 1614bytes but merely 1610bytes.
It’s beyond me, why this is the case, any ideas if I am doing something wrong or if this is a bug?
EDIT: ROS 5.22