Intercom unlock inconsistent

I have installed Ring intercom in out apartment. It has two doors and one unlock button inside apartment, so it always unlocks the door which called the apartment intercom. All tests were fine and rimg intercom can open both doors, however the unlock is very inconsistent. Sometimes it opens the door straight away, very often second attempt(ring) works, but I also had to ring it 4 times to be able to unlock. However the app always say that dopr has been unlocked, even if the unlock failed. Intercom brand is Tegui, home phone model is T-72