Is Xfi a security risk?

I have been a victim of distributed denial-of-service attacks also known as ddos attacks. on top of this i get text messages from the culprit and they are using a bot net. their words are "i am using the xfi on your modem to get your ipv4 and it allows me to hit you offline as much as i want" so i ask this. is the xfi on your modem a security risk? as my ipv4 was compromised because the newest modem does not support disabiling it .