I think i might have got booted offline and i really need to know how i can fix this

Try restarting your router (Pull the plug on it for ~30 seconds and plug it back in).

Now if you'd like to avoid getting ddosed, here's a few steps you can use:

1. Try running a VPN through your Xbox. You can find a guide on how to do this HERE (Laptop w/ Ethernet port or a PC is required). For what VPN to use too, my recommendations would be Surfshark or ExpressVPN. Lastly, avoid using free VPNs (Windscribe & ProtonVPN Free Plan) as their connections are either mediocre at best and/or cap your data usage.

2. DO NOT join random parties or reply to random messages. This is because some people are able to snag IP addresses through these methods (Xbox is working on a way to secure them, but it'll take some time).

3. Avoid games that use P2P (Pier-to-Pier) connections. These type of games make ddosing easy and its a good think to avoid them like the plague.

Gretings!

If your Internet connection is being targeted with a massive amount of requests or data, exhausting your network, none of your devices will have access to the Internet. Nor will legitimate traffic be able to pass through and have access to an inbound connection
on your local network.

Please read:
DoS or DDoS attacks: Frequently asked questions And what you should do if you experienced an attack of such kind.

Hi Issaiah C, my name is Daniel and I would be happy to help.

At the moment, the only way to avoid being booted offline is to not join random groups, not reply/send messages, and not play peer-to-peer connection games (Fortnite is not P2P, so you should not have to worry about that). If you want to take it a step further, try connecting a VPN through your Xbox. However, the downside to this is that it requires a computer with an Ethernet port and preferably a VPN with no data cap. You can find a guide here on how to do this yourself.

https://www.windowscentral.com/use-vpn-xbox-one

Note: This is a non-Microsoft website. The page appears to provide accurate and secure information. Beware of ads on the site that may advertise products frequently classified as PUPs (Potentially Unwanted Products). Thoroughly research any product advertised on the site before deciding to download and install it.

Information source (Credits): https://answers.microsoft.com/thread/2d76fdcb-2c89-4d10-8307-63eefef9bbed

If you have any other questions, please let me know.

Best regards,
Daniel.

You would need to contact your ISP to alert them to what's happening. You can file a complaint via the console and the enforcement team will investigate the other player. Calling out other gamers is not allowed on the forums.

You are able to press charges against him. Call Your ISP and notify them the situation. They will track the person down and with your consent, you are able to give him jail time.