Can't get chime to connect to my network

Hello i bought a house 5 months ago and before moving in i bought ring doorbell2 and two outdoor wireless battery cameras. When i got the keys to the house i notice he already had the first ringdoorbell installed and a chime that he left for me to keep. I did make an account here and bought a 1 year plus sub, i keept his doorbell since it was already installed and setting up doorbell and cameras was no problem and the chime was working great but a few weeks later i notice it was still register in old owners name and asked him to unreg it, sure no problem he did that right away. But since then i can't get the chime to work, it can't find my network, even when i add the numbers manually it cant find.I have looked at every guide i can find but i can't get it to work.What am i doing wrong? My router is Synology RT2600ac and chime worked when it was register on the old owner.Thanks for any help./Niclas