You have to fight them, though even if you rent and have issues they’ll blame the wiring in the house. They didn’t really like when I said I ran a new cable from the demarcation box to the modem so my wiring can’t be a problem… I really didn’t, but I knew my cable wasn’t the problem because I plugged the friggin modem right into the cable coming from the pole and still had issuesIf
If you don't use their modem and have any issues at all they will blame whatever modem you own. Yes- for the average lay person you are forced to rent their modem.