@Kevin_Z Hello Kevin, after 4-5 h of troubleshooting I have most of the information I need to deduct that it might be faulty.

Smart connect was enable since I first configured it and found it useful until last night. The main problem seems to be with the 2.5Ghz bandwidth, as it's the one that causes the main issues.

I've reconfigured the router 6 times last night each time with a different configuration to try and determine what is the cause, and every time the laptop/mobile phone tried to connect on the 2.5 Ghz or (both when combined with smart connect) it failed, or got the message that password was not correct ( have this all on screen record , even with copy paste from WiFi password configuration it failed).

When router was first booting, it took around 6-7 devices with successful connection and started dropping them 1 by 1 after 1-2 minutes.

When Guest was enabled, the connection on that part was stable the entire time but access for router configuration was gone and was able to make that only from Tether application.

When full factory reset was on, the 2.5 ghz network did the same errors with password incorrect ( the factory password ) and cable was not showing for some reason.

After few attempts the 5Ghz network appeared on the WiFi scanner and was able to connect with the factory password and make changes ( this time without the smart connect )configuring 2.5ghz and a separate 5 ghz connection. Few tests later, 2.5Ghz had kicked all the devices off the router.

Luckily for me, I always make a system backup for any new device I purchase before making some configuration, and I found the backup from the router since the day I purchased it. Made a restore hoping that it might fix everything, and had the same result.

I've contacted the store from which I've purchased the device and asked for service check as the router is 3-4 months old.

  @Kevin_Z I've forgot to answer to all of the questions:

Except for the firmware update, are there any other changes or modifications that you've ever made to the network? Will the internet LED change to orange when the issue happens?

 - No modifications made to the network ( this happened for few days ago since we got back from vacations ) initial saw that home C200 Tapo camera led was blinking, troubleshooted that and got to the conclusion that its the wifi network, started restarting the router everyhour because it keept disconnecting the video camera, then after few hours, in the Tapo application, I saw that the outside camera C310 started with the same behavior that was fixed with the reboot. After 1 day, I saw that mobile phone started having some issues with this, and when I started the laptop, noticed that I was not able to connect to the WiFi, when i fixed that in the imediat second the laptop connected, the phone got kicked from the network and was impossible to reconnect, hence I started the troubleshooting of the network.A

Now I've put in place the old Router Archer C6 AC1200 that is working with no issues since.

Do you use Parental Control or HomeShield Pro on the router? If possible, please try resetting the router to factory defaults then reconfigure it from scratch to see if any of the previous configurations may affect the wireless connectivity.

 - I don't use the Parental Control or HomeShield. And reseting the router to factory and reconfiguring it with different options for 2 times did not help.

  @Kevin_Z Hello ,

Thank you for the support, after 1 month in service, I finally received my new router. ( Backup from old one didn't work into this, and saw just after 2 hours into configuring, after finishing the dhcp clients mapping that this router is V2.0 and no longer V1.0

I want to ask you, should I update to a newer version or not ? After what happened previousely, I'm having second thoughts into upgrading the Firmware.

Can I get the information about what it's fixed/tweeked into the newer version of firmware compared to what I currently have ?

The info in "what's new" are kinda vague:

Thank you.