In both the US and Asia in the past 20 years or so, I've been able to buy my own ADSL and cable modems from third-party sellers and have that as my only CPE. Th

In both the US and Asia in the past 20 years or so, I've been able to buy my own ADSL and cable modems from third-party sellers and have that as my only CPE. This avoids the rental fee and is often a win if you're going to use it for more than a year or so. I managed to get almost ten years of service out of one DOCSIS modem before I started having reliability problems and replaced it. I don't really know if it was failing electronically or was just too far behind network upgrades that demanded newer DOCSIS features. Generally, I've shopped carefully and looked for compatibility listings to decide whether my chosen model would work with that particular ISP. You are right, with cable modems I've had to put my customized router behind it. But I purchased both the router and modem from independent sellers, not from the ISP. I even took one modem from one ISP to another with a house move. I struggled until I factory-reset it once. It seems the first ISP had pushed some kind of update for their network that made it incompatible with the second ISP, but after a full reset the second ISP was able to configure service. They never came on site, I just called them and provided the DOCSIS equivalent of a MAC address so they could remotely provision it.