You can do that by uploading a previous version of the FW. Not all FW versions can be downgraded. Find your current FW in your region support section and see if in the Notes (at the bottom)...

Have you tried to ping that domain from an external network (different ISP - not from your LAN) ? Here's a video guide for configuring Open VPN on a TP-Link router.

@regeponur Check your ethernet negotiation speed when issue occurs here: Speed of Internet port and the LAN port, where the PC is connected should be 1000 Mbps normally. If during the issue one of...

@ArcherC80User Wireless device does not support WPA3 If the Wi-Fi connection is still only encrypted with WPA2, the wireless device does not support WPA3. Although WPA3 is supported by devices with...

@Robinson_Chera Upon successful DDNS creation you have to wait a little bit for the registration to take effect, associating the registered domain name with your current IP address. If you're using...

@r0gfrog Have you changed the device configuration prior/post updating the FW ? What are your wireless security settings ? Try these for both bands: