[villagetinker]

OP, we have Xfinity also, with no problems, try the following:
1. Look at where your modem/router is located in the house, we had to move ours to a central location for complete coverage.
2. Run "www.speedtest.net" from your computer this will give you an idea of your INTERNET speeds. I would do this with both the wireless (wifi) connection and a wired (ethernet) connection.
3. For your blue tooth devices (keyboard and mouse), I would look into updating the drivers. Also, if you have a lot of these devices (speakers, earphones, mice, keyboards, game controllers, etc., these maybe interfering with each other.
4. Depending on the make of your TVs, you should be able to do an update on these also.
5. You may want to contact Comcast to see what level of Internet service you have, and if necessary you can share your results from the speedtest if it shows much slower that what you are paying for. We had a situation where the cable from the box in the back yard went bad and we were getting lots signal problems in the house, since we were renting the Xfinity modem, the cable replacement was no cost.

There a few people on this site that are very good with getting this type of equipment to work together, I am hoping one of them will reply (I did not keep their contact info) and you hire them to get your various systems working.

I hope this helps and thank you for providing the additional info.