@Wasec Try to reboot the router with the SIM card inserted into the router. And you can unplug the SIM card and plug it back to the router and repeat it several times. If still the same, you can...

@Whatdoyouwant I see, thanks for your valued reply. Try to reboot the MR600 with the SIM card inserted into the router. And try to unplug the sim card and plug it back to the SIM card slot for...

@ipourn Below is the instruction to setup the 3G and 4G Backup. https://www.tp-link.com/support/faq/2719/ Please ensure that the MR6400 connects to the main router via LAN/WAN port, and you can show...

@Creeper Replied to you.

@Creeper Thanks for your information. May I know what is the SIM card carrier? With another SIM card inserted into the MR400, does it work well? What about the wired connection? Do you still access...

@MikeMynis @JimDaniels Thanks for sharing your experiences with each other, and it will help those who have the same issue. We will follow up and try to do further analysis to locate this issue and...