One out of 4 fobs keeps stopping to work. Changed battery but made no difference. Watching a video on YouTube on a similar problem I inserted a thin paper on top of the battery to improve contact. Initially it works but stops working after a while. Already my son who is using this fob wasn’t able to enter to the apartment three times.
What is warranty policy about fobs, what can I do.?
Bei mir auch!
Der Fob will nicht mehr, habe dann die Batterie öfter rein und raus geschoben und dann geht es wieder für kurze Zeit.
Ein Hardwarefehler?
Ich habe auch den Fob 1 und da ist es ähnlich.
Ein richtiger Flop 
If you got a hardware issue please contact our support so they check if it’s eligible for an exchange.
I had similar issue with one out of three and got it replaced, now the two others are having the same issue. One entirely stopped, the other only works sometimes. We actually got back to using keys and in now we have the keypad because the Fobs aren’t reliable enough.
Try restarting the lock (remove batteries-wait 30 seconds-insert batteries), that worked for me. Nuki refused to exchange the lock.