Archer T2U Plus USB adapter on a Windows 10 PC

ISP is giving me 400Mbps and I can see that speed listed when viewing the adapter properties in Windows. But, when I do a speed test via speed test sites I'm only seeing 90Mbps. 

I downloaded the latest driver for the adapter and rebooted. No joy. 

Any ideas on what I can do to fix this? Is this even an adapter issue?

Thanks.