Authentication Error--wifi doesn't work

[abenne8]

Hi, I've had this Galaxy S6 for a year and it's always done this weird thing where every 45 minutes or so, it would momentarily disconnect from and reconnect to the wifi. This was a phone issue, I'm sure of it. Why am I sure? Because it does this exact same thing on my apartment wifi, my mom's wifi, my dad's wifi, McDonald's wifi, Panera's wifi, and my university's wifi. It was annoying but nothing more.

Recently my university made me change my wifi password--annual thing I think. After I did that, my wifi went from disconnecting and reconnecting to just straight up disconnecting and that's it. Reconnecting manually leads to an authentication error. If I turn wifi off and back on, it will reconnect but lose connection in 10 minutes. So, I wiped the cache. Nothing. So I booted in safe mode and the same thing happened, but it took a lot longer for the disconnect to happen.

Then 2 hours ago I factory reset my phone. It worked for a half hour and then the authentication errors came back. I'm currently typing this on 4g.

Note: It is NOT the router. I have tested this behavior on at least 6 different wifis, 3 public 3 private. And frankly, I think it happens on every wifi but I haven't always paid attention. I know the problem is in the phone.

How should I diagnose this? Are there any wifi logs anywhere?

Update: The crashes seem to happen when the default Facebook app is open.

 

[Rukbat]

When you hear hoofbeats ... Facebook is known as a very badly written app. When you finish using it (if you must), don't just hit the Home button and leave it running in the background, use the Back button and close it. (If you want to use Facebook on Wifi, use your web browser, and go to the Facebook web page.)

 

[nh105]

After struggling with this for months, I found the answer on another forum. Since the application of certain security patches, the S6 has trouble with two common router settings: band steering and multiple networks with the same SSID. My home router has a 2.4GHz band and two 5GHz bands. Since band steering was enabled (by default), all of the bands had the same SSID (or network name), and the router would steer the connection to the appropriate band for the situation.

It seems that the S6 sees band steering as a possible hijack. I gave each of my networks a distinct name - "MyHouse2.4," "MyHouse5-1," "MyHouse5-2." I connected the S6 to each of the networks with the password I set for each one. Now, instead of the router selecting the band, the S6 selects it. And it seems to be OK with that - it stays connected much better.

Unfortunately, if you're trying to reliably connect in a work environment where there are many bands (or even many routers) with the same SSID, you might be out of luck. If you're at your desk all the time, you might grab an old router, plug it into an Ethernet port, and create your own network that the S6 can handle.