Is there a fix ?

Possibly. For some people. There is a firmware that addresses the latency spikes and detects and mitigates the DoS. This firmware has only been rolled out to a small number of devices on a limited number of ISPs. There is also a "Packet of death" issue that causes the modem to reboot.

The modem, even when fully patched, still has performance issues and is not the equal of a Broadcom

These issues exist in Puma 5/6/7 based devices.

Many modem makers have not updated firmware

Many ISPs have not rolled out new firmware

A number of ISPs NEVER update firmware on customer owned devcies