S24U trouble connecting on 5GHz WiFi

[teh0wner]

Greetings all. Been having an issue with my freshly arrived S24 Ultra which is doing my head in and was wondering if anyone else is having the same issue and/or knows of a fix.

At home, I have a number of 2.4Ghz and 5Ghz SSIDs. Some combined, some not. For whatever reason, it seems the S24U will not connect to the 5GHz one(s). I can see it automatically tries a number of times (maybe 3-4) to connect and eventually I get a message that "connection has failed". I've tried absolutely everything:

* Factory reset S24U
* Restart router/access point (I have a Unifi Dream Machine Pro & U6-LR)
* Update firmware on both Router & AP
* Switch between 2.4Ghz, 5Ghz and combined SSIDs. S24U will only connect when it's 2.4Ghz
* Try WPA3 + 5Ghz (didn't work)
* Disable all SSIDs and leave only 1 at 5Ghz
* Enabled WiFi Safe-mode in Developer Options

I've dumped the logs as well but couldn't make much sense of them. One interesting line was: "Connect <mac address> <SSID> is FAILURE. cmid 0xc000003 reason 8 status 65529 (google yields nothing)

I've had S9, Note 10+, S22U, S23U with no issues. Nothing from the above helped with the S24U though. Appreciate the help. Thanks in advance

[Steven Goh]

I have followed your method and the result is the same.

[Dhruv Patel]

I have similar issue with my S24U and iqoo 9 SE,

When I connect to the Airtel Mesh router then it gives limited connection, wifi gets connected but, no Internet.

However, The Whatsapp works that is strange.
With my Main router everything works, no issue.

[BGCMinime]

I also tried a lot of stuf, on my phone I reset my wifi and bluetooth settings, reset phone, reset in safe mode, deleted a few apps, turned wifi on and off, deleted the 5G connection, added it mannually, then, on my router, changed the "Channel control" to "Automatic" or "36" or what ever option needs to be able to detect your 5G WiFi on your mobile device but nothing of these attempts worked for me so I searched deeper in my router config. (btw, my router is: Asus RT-AC1200G+).

 I was thinking to check the ipv6 configuration on my router first but something just got in mind, so what I did to solve was to check my router's configuration for WiFi settings, changed some settings then I checked the "Wireless - Filter MAC wireless" and add my SG S24U there in the accepted list because I activated this option, if you have the same issue, then either add you mobile phone there in the MAC list, by adding your MAC address found in your WiFi 5G connection configuration or just turn off this "Wireless - Filter MAC wireless". But you might also need to check your other WiFi / Wireless configuration on your router as well as checking your ipv6 just like some other members here reported that the ipv6 set to disabled on the router might solve this.

Just keep in mind, please, that your phone is fine, there is no factory defect, because there is a very high chance that some configuration is blocking your WiFi 5G connection, either from router or from an app installed on your phone. Best approach I would recommend is that you first need to determine which is the root cause, so I would suggest to try it with your Router configuration, check everything possible there and if that doesn't work then restart your phone in safe mode and check if there 5G works fine or not,  but if that doesn't work then do a factory reset on your phone and if still doesn't work try to connect your phone to a different 5G wifi network (your friend or a public one etc) and if that still doesn't work then maybe then, just then, you might want to contact Samsung support or your local seller.