If you are having issues connecting to your Qnap with Qremote on your Samsung you can try the following: Disconnect your wi-fi on the Samsung and reconnect it. I had the same issue with my Qnap 469L and that solved my problem on my Samsung Galaxy Note 4. If you are still experiencing issues try rebooting your Qnap. If that didn't work try unplugging your router and modern for a minute and then plugging them back in. Lastly, uninstall Qremote and reinstall it. One of the above methods should solve your problem.