Phone shows WIFI as connected but has no internet access

[MakTavish]

Hello there, for the past 2 months or so i've been having problems with my phone (Tesla Smartphone 3.1 lite) where at the top of the screen i see the wifi icon, but trying to load anything that requires internet does not work (turning the wifi off and on fixes it for around 1-15 minutes). Using mobile data has the same problem but only on apps like instagram or facebook messenger. I am fairly certain the problem is with the phone due to the fact that my mothers lenovo and my PC have no issues whatsoever. I tried looking the problem up but all the threads i found ended with "found the solution myself" without the answer itself. I tried a factory reset but it didn't fix anything. At this point any ideas are welcome except getting a new phone because i am currently unable to do that.

 

Since the phone is probably not very known, here's the link to the site

https://tesla.info/ea/phone/smartphone-3-1-lite/ 

And a link to the phone specifications

https://tesla.info/wp-content/uploads/2016/07/Tesla-Smartphone-3-1-Lite-Data-Sheet.pdf

[tikker]

Same here with my Galaxy S4, not sure what's causing it and some days it happens more often than others.