Just successfully claimed EU261 from QR over a missed connection in DOH.
Delayed arrival into DOH (from EU) was 2.5hrs late, missed my 1hr connection because of it, next flight got me to my final destination 5hrs later.
QR denied my request for EU261 twice, on the third email to them by myself, sending them a "guidelines to EU261" (official EU document) as attachement, they gave up and let the local QR office send me my compensation ^