Why am I getting “DoS attacks”?

I have a BGW210-700 gateway router. This is my second one and I am still having same issue. Someone is sending “DoS attacks” according to my logs on my router. When that happens, everything stops working even tho my wifi is still up and running. Internet will still be up but things will load slower and devices will lose signal and when I try to reconnect, it’ll say wrong password when it’s right. Everything will work fine again if I reset my gateway but then I have to redo my configurations again and it’ll be good for a day then happens again. How do I get another model equipment so I can have a different Mac ID router? Because I think that’s how they are able to “dos attack” again if they have my equipment Mac Id and IP…. I have my security feature on. I’ve tried resetting factory and I’ve tried Mac ID address filtering but they just spoof another random Mac ID. I’ll also get odd devices connect that I don’t own but when I trace their origin, it doesn’t exist…. I don’t know if it’s the router itself that’s infected but this is my 2nd BGW210. This one is actually worse than my first one. My first one happens every 6-7 months. This one is like every week.