Is there an actual app that helps diagnose wifi connection issues? My s8 connects to my isp router at 2.4ghz and when tap the wifi icon, it goes to 5ghz, I'm getting random wifi disconnect msgs too. I noticed my s25 goes offline at the same time. Makes me think I'm hacked...
You're likely not hacked. The issue is that your router likely has the two bands bridged, and the phones have a hard time separating them and creating a stable connection. If you know your way around router settings, separate the bands and make two separate networks. Then connect your devices to one or the other. If you don't know your way around the router settings, ask your ISP to do it.
I've replaced the modem/router yesterday which seemed to be fix things. But nothing changed. The tablet should connect at 5ghz but only will at 2.4ghz. Its been acting up for 4 weeks or so. I used the developer tools and reset the wifi subsystem without luck. My ISP is useless. Xfinity doesn't have any experienced techs. Trying to get a level 2 or higher to troubleshoot this isn't possible. They came yesterday and swapped the modem out without change. He didn't even verify my conclusion of the problem.
Fwiw, and I know this isn't really the point, there is no discernable difference in speed, that I have found, between your device connecting at 2.4 and 5ghz. If you have a stable connection at 2.4, you should let it be - it's much more stable, longer range and less prone to interference than 5ghz. Personally, I'd still keep (and do) the bands as separate networks. I've been seeing that many people with certain devices have had issues with the bridged bands after this specific update. I still believe that when the networks are combined, intelligent wi-fi keeps switching between the more stable band, and this can occur many times within the same location as you move around. Devices can even become confused as to which band to connect to and stay connected to. I had this issue with one of my security cameras.
