Unknown wifi issue! Please help!:(

I have a ps3 a Mac and an iPhone. I never usually have problems connecting or loading webpages and such. Two days ago I noticed that apps on my iphone that required Internet service like Instagram wouldn't load. I tried disconnecting and reconnecting everything.

Now this is where it gets weird! I can get a good connection on my iphone but when I connect my Mac everything just get screwy! Both devices show that they are still Receiving signal though. I can sign into my psn after I reset my router and modem but as soon as I reconnect with my Mac I get signed out. My ps3 can obtain the ip but it can't establish an Internet connection claiming to be an error with dns.

I was looking for anything that could give me a clue of what is really going on and i found that my iphone and Mac keep changing ip addresses when I mess with my router and modem. My Mac will say there's another device using IP address. When I look at my router logs though there isnt. I only see ip's for my Mac, iPhone, and pc. I have also tried leasing and renewing each devices ip. Not my pc but router, iPhone, and Mac.

I apologize for such a long story I just really need to fix this problem so I know the best way is to give all info!

Thank you for any and all help!