Wifi broken

[Boyla]

I've been having slow internet over wifi only for the past couple of months. I was hoping it was just a problem that would fix over time. My ethernet connection speeds are fine but my wifi connection speeds are weird. It takes about 30 seconds for any phone in the house to load anything. Snapchat for example will give me notifications but when I launch the app I have to refresh manually and it takes about 30 seconds for it to update and after I refresh the connection goes back to being normal/ fast. I recently tried changing channels for my wifi and seeing the quality through an app called wifi analyzer. The channel that my wifi broadcasts on has the lowest rating but when I switch to a different channel, the channel that I switched too then goes to the worst rating. I've tried all of the channels and same result... Speed test on my phone takes a long time to connect but once it does I get normal speeds (70Mbps down and 5 up). I don't know what to do at this point.