[Marc F2]

Settings --> Wi-Fi --> Advanced --> uncheck "smart network switch"

[OverSeventy]

I had similar problems as you describe, it drove me insane. However, I stumbled onto a solution that may assist you as follows.
Go to Settings, select Wi-Fi. If the "Smart Network Switch" option has been checked, uncheck it. I found that my Wi-Fi Dowload/upload stabilised with no further drop outs . My phone still pairs seamlessly to Data Network and my Home Wi-Fi Network, battery life has improved as well. I've not encountered any other difficulties. Hope this will assist.

[OverSeventy]

I had the same problem, VERY frustrating. Try the following:
Settings, Wi-Fi, Disable "Smart Network Switch" It claims to switch (seamlessness) between wi-Fi and mobile networks, however, since I've disabled haven't noticed any change in way it connects. My battery life has increased by half a day and my Wi-fi connection speeds have improved. Give it a go......

[heebster16]

Upgraded to android 5.0 this morning. All good except wifi does not work after using hotspot. Hotspot works, but after using it the wifi reconnects but does not transfer data. A restart of the phone fixes wifi again (until hotspot activated and deactivated.)

[ProfoundlyJaded]

I unchecked the smart networking option and am not having trouble at all. Hope it worked out for you all!

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[Paddo57]

My problem seems similar except that my Wi-fi seems to connect OK but while the WIFI icon is showing connected, I have trouble connecting with the internet. I go to Google, pick out a random page and it seems to take forever to load the page if at all. I've tried re-booting my Galaxy S5 and modem and it seems to take a couple of goes for it to work. But since last weekend I'm getting next to no Wifi service on my Galaxy despite the phone indicating that Wifi is successfully connected. I don't have this issue with other equipment. My PC and my TV I-view work fine using the internet.
I was away at the weekend but was able to use my friend's Wifi without any dramas. In fact it connected immediately. I've re-entered my modem ID and password a few times. Tried changing WEP to WPA/WPA2/PSK. I will re-try it when I get home tonight.

[BrewGoggles]

My phone is having a similar issue only different. I will connect to a server and it will be fine for about 30 seconds and it will disconnect and reconnect if it does disconnect and forget how to reconnect first. I can't find any way to fix this issue. Can somebody please help me?

[BucketsofFun]

Thank you for the tip on re-inputting IP address. I could not get it save the "static" setting. WIFI works perfectly now! Yeah!

[rpenaloza6035]

I have the exact issue that Ike Hustle has.
The Wifi on my S-5 worked perfectly until the lollipop update. After that my wife did not work at my office. Wifi works at my home and pretty much everywhere else. The phone identifies both the staff and guest wifi network but when trying to connect it just says saved but never connects. I discussed the problem with our IT people and they checked and my phone is not being blocked. Everybody else that works around me has no problems connecting to the work Wifi so I know it is my S-5. Has anybody figured out how to solve this? I have tried changing to static but this does the same thing. I thought with the Marshmallow upgrade the problem would be fixed but no such luck. the same problem exists. Any help out there?

[japark]

I have the exact issue that Ike Hustle has.
The Wifi on my S-5 worked perfectly until the lollipop update. After that my wife did not work at my office. Wifi works at my home and pretty much everywhere else. The phone identifies both the staff and guest wifi network but when trying to connect it just says saved but never connects. I discussed the problem with our IT people and they checked and my phone is not being blocked. Everybody else that works around me has no problems connecting to the work Wifi so I know it is my S-5. Has anybody figured out how to solve this? I have tried changing to static but this does the same thing. I thought with the Marshmallow upgrade the problem would be fixed but no such luck. the same problem exists. Any help out there?

I had that problem at my work (galaxy s5, marshmallow). Tried changing various settings and rebooting with no effect. Phone continued to connect fine anywhere else. Finally tried clearing the cache (again) and the problem went away. Don't know why the problem developed nor why clearing the cache fixed it.

[Rich Veeck]

I may be done with Samsung phones after this one! I have a brand new Galaxy S5 Active and it will not work well on wifi and is driving me insane. All it does is clock and hang, and then periodically tell me it will reconnect once the network improves. Then it connects and disconnects constantly. I tend to leave wifi off because it is unusable. Sad.
A poorly designed phone?????
Should I return it and Fogel about Samsung till they can fix their phones?
I see people here posting things like, go into the trouble network, click edit and advanced and change IP from Dynamic to Static. What are people talking about? When you select the network name, the is no Edit and no Advanced and no Static setting. There is a general Advanced setting on the main wifi page but no Static IP option.
What is happening?
I am ready to return this and get a better phone that works on wifi! Ugh!