@ThommyMD Hi, Please download the firmware from TP-Link official webpage. Archer MR600 V2 Since your current firmware version is relatively old, please upgrade it one by one from the earliest...

@Hotzenplotzer Hi, Please check if there is any advanced settings on the router like Mac filtering or block list that may block the internet on your Samsung phone. And connect the phone to other WIFI...

@egi2024 Hi, Please insert the same SIM into another LTE device or even a smartphone to check if the SIM has a problem. You may try to change the Network Type on Advanced > Network > Internet page...

@Jazz923 Hi, I noticed you posted another thread on the forum. I have responded and sent you the beta firmware via private message.

@Jazz923 Hi, I have send you the beta firmware via private message. Please check.

@Victorboris1 Hi, It is likely to be this issue. Wi-Fi Range Extender Causing Host Router No Internet