@Riro2023,

Have you been able to check either the Tether app or the WebUI to determine if there are any issues that could have caused this?

When you are able to get a connection on some devices to the internet, it is almost always an issue or incompatibility with the routing of the network. 

Most often, unstable connections that come out of nowhere are a result of an update to either your modem or router that changes the operation mode. Depending on what type of modem you have from your ISP, make sure that there is not a wireless signal being broadcast from the device, and make sure that the toggle for either IP passthrough, or bridge mode is enabled on the modem (this can be done via the WebUI of your modem, or via your ISPs app. If you were previously using the Archer router in AP mode, make sure that this has not changed back to the default router mode.