Slow wi-fi connection on iPad Pro 10,5

Hi there,

I have problem with the wi-fi download speed on my iPad Pro 10,5 Wi-fi 64 gb now with iOS 11.2.6, but I had this issue on previous versions too. Wi-fi download speed is too slow (2 mbps), even I have a 100 Mbps connection. It works fine on iMac, on my iPhone, but not on iPad. I tried almost everething (restart, reset, reinstall iOS using ipsw file). I found kind of solution on internet today. When I turn off BT, download speeds are ok (about 100 mbps) when I turn BT on, wi-fi download speed is arround 2 mbps again. But I want and need my bluetooth connection turned on always. What should I do? Thnks