Having bad ping on fortnite with 300mbp Nighthawk router/modem

I've been having similar issues. I have Cox's panoramic modem/router combo, 500mbs down/10mbs up. Playing warzone with 27 ping then it'll spike to 80+ ping with the packet burst symbol. Did a ping plot and I get packet loss of .5-9.8%. They updated my signal but still suffering. 

I have been battling Cox on these issues for just under a year now since COVID started. The problem is nearly all of their nodes that your modem is directly connected to are well over 100% utilization which causes incredible packet loss and spikes. The internet speeds usually aren't effected but the latency and packet loss is definitely noticeable. There are two things you can do and that is to file an FCC complaint about the packet loss and you will be able to talk to their actual engineers who are "diligently" working to split these nodes to help with saturation. They will probably give you some date that is months and months away when your node will be fixed and they get away with this without even a slap on the wrist because they have a "plan" to fix it. The ISP monopoly has been a travesty for years and COVID has only made it much worse and noticeable. The second thing you can do is go to https://fairshake.com/ to ask for a settlement to reduce your bills or pay you back for their service they aren't able to reliably provide. Don't take the first offer because it will be very low for what they actually deserve from this country wide failure.