@TPUserBob So, it looks like the bottleneck is probably my old wifi router. The WAN port is only 100Mbps. I've ordered a new one that's 1Gbps so we'll see.

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...