Am I dealing with a crafty DDOS attack?

I am an Xbox gamer. I have been dealing with an person who has used his skill set to ddos me. It’s proven via messages (reported messages MANY times and nothing has been done). I believe the intensity of the attacks have increased to a much more severe type of an attack than your traditional ddos where you reset the router/modem and you are good. Over the last 3 months I have been booted offline and dealing with tons of lag often leading to no connection. At first it was just a disconnection and as time progressed… three months later here I am almost on a timed schedule where I lose internet from 11am and regain internet around 10 pm. At first it would go out around 1-1:30pm and come back around 7pm. Everyday over the last week that gap has become larger and larger increasing 15-30 minutes on both ends leading to almost 12 hours without internet. I have talked to my isp MANY times and they have replaced every bit of line from the street all the way to my house and no results “everything seems to be running fine on our end”. ISP telephone support tells me there is signal to my modem but no signal back. I have used multiple different setups, 2 different types of modem and router setups, and I have tried using a single Unit modem/router. None of which are able to connect to the internet from 11am-10pm (exact same issue reguardless of setup). Times are not exact but within a 30 minute window of those times every time every day. I obtained a VPN, that too has made no difference. I have played with wall outlets on both sides of the wall to check for interference and nothing has changed. Most times I am home alone with nothing but my Xbox and normal everyday appliances running. With my ISP so clueless to a resolution, this leads me to believe a more serious ddos attack is taking place. Any advice/help would be highly appreciated. Thank you!