@kalaka Hi, Please check if you need to enable UPnP for this device. And you can also check the settings on the old router, whether you have set up advanced settings for this certain device like port...

@JohnGhost Hi, It is recommended to set the backend devices to automatically obtain an IP address via DHCP, and also reserve an address for the AP on the main router. This can help the main router...

@JohnGhost Hi, UPnP opens the corresponding ports for devices based on their requests. If one device is already using internal port 3074, another device won't be able to use that same internal port...

@Ame180 Hi, Thanks for your update. So you mean all the devices have the unstable issue now? Please try the troubleshooting suggestion we provided earlier and switch the LAN port before testing...

@artcza Hi, Please check if the SIM card works normally in devices like another 4G router or cell phone. Besides, if the router can get an Internet IP normally, you can also change the LAN DNS to...

@Edik13 Hi, Please refer to this thread to do the troubleshooting steps.