Someone else mentioned the Netgear NightHawk modem and I second that. I have used one for a number of years with no issue. It is Comcast compatible. Model CM2000. The router and all network components are Synology.
I also use the iFi LAN I Silencer product in various spots on the network and do think it made a positive impact on music streaming/playback. You might even give this a try before you upgrade equipment.
https://ifi-audio.com/products/lan-isilencer/