Wifi and data suddenly very slow on S5?

[Android Central Question]

For about the past month, my phone has been exceedingly slow on both WiFi and data connections. Other devices on my home WiFi network are running smoothly, but my phone is barely usable. This happens for every app I've tried—the Google Play Store, Firefox, Spotify—all very slow.

Perhaps most bizarrely, running a test on speedtest.net doesn't reveal any issue; my ping is 23ms, my download speed is 71.33Mbps, and my upload speed is 1.59Mbps. However, trying to play a song, download a file, or load a webpage (including speedtest.net itself) remains a glacial process.

If it helps, it's an i777 Verizon branded Galaxy S5 (model number SM-G900V) running Android 6.0.1, and for more than a year prior it has worked perfectly. Any idea what could cause the sudden switch?

Thanks so much for your help!

 

[B. Diddy]

Welcome to Android Central! Just to be sure -- it's still slow if you turn off the wi-fi radio?

Does this also happen in Safe Mode? https://support.t-mobile.com/docs/DOC-28456

 

[Cosima1]

Same situation; I now have set my phone to connect to my 2.4GHz, not 5GHz network and it seems to work fine.
I got this solution from another thread on here.
Glad to not have to get another phone!
Also, previously I had done a wipe cache partition and factory reset to no avail.

 

[B. Diddy]

Thanks for the input! In your case, it's possible that the wi-fi signal strength for 5 GHz was too weak where you were sitting in the house, thus causing the slow speed. 2.4 GHz has significantly better range than 5 GHz, so switching to 2.4 GHz would've led to a stronger signal and faster data transmission.