Internet download speed is slow

Hi Cox Support,

I'm experiencing recurring issues with my internet connection that I need help resolving. I’m on the 500 Mbps plan, and my download speed works fine for hours, days, or even weeks, but then it abruptly drops by about 95%, down to 25 Mbps, until I reboot the modem. The upload speed remains unaffected. In hopes of solving this, I upgraded to the 1 Gbps tier, but the issue persists—tonight, the download speed again dropped to 25 Mbps until a reboot.

I live in Scottsdale, AZ, and have had around a dozen technician visits over the past six months. While technicians can see the problem, they haven’t been able to find a solution. Despite suggestions to switch to the Panoramic router/modem, which they thought might help, the issue continues. Senior technicians have also been to my house a lot, but remain stumped.

We’ve already taken these troubleshooting steps:

1. Tested signal strength with both contractor and Cox employee equipment.
2. Replaced all internal wiring—twice.
3. Installed a direct, unsplit coax line from the modem.
4. Replaced all coax cables between my house and the hub (only 50 feet away).
5. Replaced modem cards at the hub, as suggested by the techs.

Is there anything further I can try, or additional support that can be provided? At this point, the senior techs are throwing up their heads and just guessing, Like saying maybe it's my electrical system somehow, but it's all speculation. Your help is much appreciated.

Thank you.