Is XFINITY the culprit of our slow speeds and intentional misleading information?

I've been experiencing extremely slow speeds for the past three months, and it seems like XFINITY is deliberately providing misleading information to push their "supported" routers with fixed monthly fees in order to phase out third-party devices.

For two years, I used an Arris S33v2 modem DOCSIS 3.1 (rated at 2.5Gbps) and an XR1000 router, and for two years was consistently getting just under 1Gbps speeds (around 930Mbps). Then, one morning (DEC 2024), my speed suddenly dropped to 300Mbps. To rule out my equipment being the issues as they undeniably said it was, I purchased a brand-new Arris S34 ($250) modem and an ASUS ROG Rapture GT-BE98 ($689) router from Best Buy—yet the issue persisted whilst claiming it's my devices not supporting the speeds for my plan. Clearly my devices old and new support speeds more than my plan offer.

Over the past two weeks, three technicians have visited, countless "firmware updates" and "modem provisions" were performed by tech support, and all coaxial ports were checked (they confirmed they can easily pull 2Gbps). I even have multiple CAT 6E and CAT 8 Ethernet cables, but XFINITY insists that my devices are the issue—even the brand-new ones I bought specifically to test their claims.

Both modem and router manufacturers ran diagnostics and confirmed my equipment is not at fault. The problem comes down to XFINITY, and they refuse to help—unless, of course, I rent a modem from them, at which point ALL my issues will supposedly disappear.

On top of that, I’m forced to chat with an AI troubleshooter for 20 minutes every time, repeating the same useless tests only to be told there are "no issues." Meanwhile, my router's interface logs scheduled benchmarks, and I can see the deception happening. XFINITY experts seem more focused on pushing rental modems than actually fixing the problem.

WHERE IS THE TRANSPARENCY? Is this fraud & abuse? Frequently I have seen countless individuals experience this exact same issue.