Haven't yet noticed where anyone has mentioned "AX" technology.
Google "Wireless AC vs AX" for more info. It first came out I think about 5 years ago.
I suggest looking into it before buying new hardware. Otherwise you may be upgrading again sooner than you think. That includes if you buy a new computer, upgrade it to the WiFi 6 (AX) The computer must also have the AX technology to fully take advantage of it.
Since you asked, I am of the opinion to own your own equipment and NOT rent.
Also to buy separate cable modem and WiFi router.
Your SB6141 Router is aging and unable to get the speeds often needed today.
Those with few WiFi connections may find it to still be fine though.
I chose "Arris SB-8200" cable modem
and "ASUS RT-AX82U" WiFi Router
Just make sure that you're getting what you're paying for.
Won't get higher speeds if the internet provider is not providing them.
Speedtest by Ookla - The Global Broadband Speed Test