Not getting advertised speeds

Recently I have noticed a huge slow down in my internet speeds.  Web pages were slow to load, applications were slow to update incoming data, etc.

 

Checked 8 different speed test sites:

Sourceforge: 

Ookla: 

Fast.com: 

AT&T: 

Verizon: 

Google: 

Xfinity: 

Speedofme:

File won't load, but it was 52mbps down/22 up

 

As you can see, more than half of the tests are showing less than half of my normal download speeds, while xfinity/verizon/google fiber all show normal speeds.

 

Any ideas or recommendations?