If you own your own Motorola SB6121 or SB6141 then don’t let comcast / Xfinity tell you it’s EOL end of life. Even their own documentation will tell you this.
See this link for the SB6121 and this link for SB6141 details.
Of course I just wasted countless hours because my modem couldn’t been seen on the network, had a tech come over to tell me that it was EOL and rented me a new one.
Why a multi billon dollar company can’t get it’s employee to read a simple bloody memo I have not idea.