The default L2MTU of the ports of the RB5009 is 1596 on your RouterOS version 7.22. For a long time on older versions it was 1514. Just edit the interfaces and set L2MTU to 1596 is enough. Note: 1518 in this changelog entry is a typo!
EDIT: If you've downgraded your version to long term then use the old 1514 value.