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