Photos killing internet connection for entire network in El Capitan and Sierra (solution)

I hope this helps someone out there. It took a lot of research and trial and error to figure out. This is a solution, and not a question, so moderators, please put this in the proper area - I am sure this is probably not the right one.

ISSUE: My internet connection crashed and this had been the situation for the past several weeks. I was using a hotspot from my phone for connectivity it was so bad. If I would run a speed test, it would register .03Mbps. Internet company came out (twice), replaced everything, new modem, switched, everything. Modem was getting a strong signal but it wasn't reaching any devices. Spend literally days trying to figure this out - running constant speed test. Kind of a fluke, but I noticed if i turned off my wi-fi antenna, my other devices got full internet back.

This is my note to the At&T internet tech:

"I figured out the problem - its a mac issue. If you ever see this again, this is how to diagnose it. If they have a mac running El Capitan or Sierra (the two newest versions), it will have a feature for the Photo program that tries to upload the entire library - and sometimes loops endlessly (this is the bug). When it does, it will take ALL the bandwidth and choke off the internet. The way you can tell, if you turn off the WIFI antenna on the mac, and the speed goes back to normal on all other devices. You can see this if you look at the activity monitor - Application Folder->Utilities Folder -> Monitor Program - >Network Tab. You will see a function sucking the bandwidth called NSURLSESSIOND. Immediate fix is to launch PHOTOS, Click on PHOTOS->PREFERENCES->iCLOUD TAB, either unselect ‘iCloud Photo Library’ or pause the photo updating (it does this for 24 hours). Network activity will go back to normal, connectivity issues solved. NOTE: You will still have the problem if you hardwire the computer to the modem, so wifi isn’t the issue."

Hope this helps someone!