xi6-A bluetooth connectivity issues with AirPod Pro 2

I have an older Flex box (xi6-A) and wanted to connect to it via bluetooth with my new AirPod Pro 2nd gen earbuds.  The flex box was able to find my AirPods and connect to them.  When I tried to play any content on the Flex box, I didn't get any sound in the AirPods.  I did a live chat with an Xfinity agent which long story short, resulted in the agent stating that I had to return my Flex box to Xfinity for a replacement.  The agent stated that "there seems to be a compatibility issue."

So off to the Xfinity store.  I was told that that model wasn't stocked in store and they would have to order one to ship directly to my house.  Ok, sounds reasonable.  After trying to enter the order the Xfinity rep stated that the replacement box couldn't be shipped as it wasn't compatible with my modem.  Huh?  I do have my own modem, an Arris SB6141 which was on Xfinity's approved list when I signed up.  To this date, it's been working flawlessly.  I just checked Xfinity's approved list and now the SB6141 is listed as not supported.  If I click on the view details link I get some conflicting information.  It states that the device is not supported, but then goes on to state "This device is compatible with your service download speed of 50 Mbps."  So how is everything working?  Interestingly the Xfinity rep at the store didn't mention this minor detail.  He stated that the replacement Flex box was not compatible with my modem.  I told the Xfinity rep that this wasn't worth all of the time I've already wasted just trying to get a pair of ear buds to work and left the store with my old Flex box.

Just for fun, when I got home I tried to connect my Sony WH-1000XM3 wireless headphones to the Flex box and it worked.  I'm able to hear sound through the Sony headphones when connected to the Flex box via Bluetooth.  Why?  Here are my theories:

1.  The AirPod Pro 2 earbuds now support Bluetooth 5.0, the Sony headphones support Bluetooth 4.2.  This really shouldn't make any difference as Bluetooth is always backwards compatible -- or it used to be.   Apple reports on their website that the AirPod Pro 2's will connect to other non-Apple equipment via Bluetooth without issue.  The fact that the Flex box does connect verifies that statement, but because there isn't sound is it a Flex box problem or an AirPod problem?   I'm going to say Flex problem as my Sony headphones connect and work properly.

2.  I don't understand what my modem has to do with a replacement Flex box working.  I connect the current (xi6-A) to my network via an Ethernet cable.  If I'm able to get a network signal to my other network devices (59 devices online as of this moment including the Flex box) why would the current Flex box (or any version for that matter) care about the brand of modem?

3.  When the live chat agent was helping me, he never asked if I had tried rebooting the Flex box - tech support 101.  He also reported that he ran diagnostics on the Flex box and subsequently sent it updated instructions.  Not sure I believe that as the Flex box like any other networked device gets a DHCP address from my router and that address isn't visible from the outside.  Even though Xfinity can access my modem, I'm not sure it can see let alone communicate with one of my network devices.  Furthermore, the Flex box doesn't appear to have a web interface.  If I try to access the IP address inside my network, I get an error.  If the agent was able to do what he said he did, why didn't he just remotely reboot the Flex box?  After the new instructions were sent, he requested me to initiate a reboot.

Final thoughts.  So what happens when one day my current Flex box stops working?  I guess I go without that convenience as I was told that replacement units aren't compatible with my modem.  Again, this is a device that like any other network device should work by just connecting to my home network.  Perhaps there's a secret chip that looks for an Xfinity supplied modem?  If that were the case, the current Flex box wouldn't work as I just discovered that my modem isn't supported -- but it works.

Lastly, before I turn in any old equipment, I like to sterilize it first by doing a hard reset.  I've looked at the forum and there doesn't appear to be a way to do this with my particular unit.  There should be a way for the consumer to wipe the device.  I don't trust that it will be done after it's turned in.  Call me paranoid.

While I don't really expect a reply from anyone, I want to get this info out there so someone else might read what I've been through and doesn't waste their time trying to get these two pieces of tech to communicate properly.