Wifi slow as can be with ipv6

When connecting to the business gateway wifi (android) it takes forever for the internet to work. I installed an app that allows me to disable ipv6 and then the internet is blazing fast on the wifi. I have a router also that does not have ipv6 enabled and when connected to it, the internet is great also. 

It is only when connected to the gateway wifi and having ipv6 enabled on my android cell that it takes forever to start a download or update an app. It has been this way for months. There has to be something wrong with the ipv6 config or some other settings. 

The modem updated last night in the middle of the night, so I thought I would give it another test. Same, just lags for 10-15 seconds for my android on wifi before it does anything. Load up any app, then wait a good 10-15 seconds for it to start updating/downloading etc.