@Zdzislaw To assist you efficiently, I've forwarded your case to the TP-Link support engineers who will contact you with your registered email address later. Please pay attention to your email box...

Before following this thread for troubleshooting, please do confirm the VPN problem type based on VPN usage scenarios described here. For VPN Client related issue on TP-Link Routers, please refer to...

@Georgi7 Hi, please confirm if your MR6400 is EU version V5.20, if so, you could download the latest firmware from our official website and update it to see if it solves the problem: Firmware...

@mulc Hi, thanks a lot for the feedback, I've reported the issue to our senior engineer, once there is any available solution, I will let you know.

@Bugzee Hi, please refer to this thread for troubleshooting: LTE keeps disconnecting

@vipkry Thanks a lot for the sharing!