Loud feedback noise when answering via app

I have a ring intercom, connected properly via the app instructions to an Tegui Horizon 0E7020. 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. I have been playing with the audio levels on the app but it makes no difference. This only happen using the app, the phone works fine.
How can I avoid this?

Hi @user76783 . Welcome to the Ring Community!
We’d be happy to take a closer look at this with you. Please send us a clear picture of the wiring and another picture of the case of your current intercom where we can see the model number. Our team will then be able to investigate this further. We look forward to hearing back from you.

wiring
a6-1
a2-5
a3-4
a5-3
a1-2

Hello @user76783, Thanks a lot for providing this much information and the pictures. This helps a lot already. Our team is taking a closer look at this for you and we will get back to you as soon as we know more.

Hi @user76783,
I am so thankful for your patience.
I have sent you a private message with your personal reference ID.
Please contact our Ring Intercom customer support by emailing or calling our team, and we will be more than happy to take a look at this with you. You can find our support number here: Ring Intercom Support. We look forward to hearing from you.