I have the same NVR and although I did get it updated to 3.3.4 at one time, I had some problems with it. The main one that I noticed was not being able to change the camera's recording fps for events (ie, motion, line crossing, etc...) which was a big let down for my preferences. Since I couldn't get it to work, I went down to 3.3.2 and was able to get all the options working. Maybe there were other problems with 3.3.4, but I didn't bother to check. I do know some people having issues with emails not working with 3.3.4, but not all. Guess it depends which NVR model you are using, and based on the info I've read is mostly the DS-7608NI-E2/8P. All the information about upgrading is here in the forum, but I must warn you that is not as simple as just finding the firmware and upgrading from the web gui. For a DS-7608N-E2/8P depending on which firmware version you have, you will need to follow a specific order and will more than likely need to modify the language flag for them, except the 3.3.4 (you will need the Chinese firmware). Good luck.