@Boik Make sure that your ISP doesn't use any specific VLAN for Internet connection: or ask your ISP if you need to use a router MAC clone feature:

@Nick82 VR1210v is an ISP provided device which probably doesn't support any mesh technology. Although you can connect the second modem as an AP to the main one using this guide and name its SSIDs...

@Leigh13 You're adding a client when you connect a wireless device to the RE220 wireless SSID. Here's how to configure RE220 using the WPS method.

@M_096 Follow this thread suggestions for your issue.

@PlanktonPete This is an ISP provided modem router with internal antennas. Your ISP should provide any related documentation and guidance. From Italian support website you can see its LEDs...

@Koushik7788 Follow this FAQ to determine your router local IP address. It matters if its 192.168.0.1 or 192.168.1.1 - open the correct IP address in your browser.