Extremely loud feedback noise when answering via app

Hello,I have a ring intercom, connected properly via the app instructions to an ELCOM HT-Universal 2. I can open the door without any problems via the app but when I answer the door via app the outside com of the doorbell makes an insanely loud high pitched noise, likely feedback.How can I avoid this?I use the cable A, A1 is connected to 5, A2 to 6.