According to Amazon, Romania has access to devices on the Amazon UK store. There you have access to TP-LINK products. I've used close to a dozen of their
TL-WR802N portable, multi-mode wireless devices to give a wired-only devices wireless ability such a laser printers and older gaming consoles, by using it's "client" mode. There's also a dual band version, the
TL-WR902AC.
There is no software or drivers to be installed on your DVR, gaming console, TV, etc. Your device "thinks" it's plugged into a LAN cable.
You connect it to your LAN, run the wizard, select "client" mode, give it a unique static IP (in the same subnet as the wireless router or access point you want to connect to but outside of the router's DHCP pool and a subnet mask of 255.255.255.0 and gateway IP equal to the LAN IP of the Internet-connected router), have it scan for the SSID of the wireless router, select that and enter the wireless password. It will connect to the Wi-Fi. Move its Ethernet cable over to the NVR/DVR which is either in DHCP mode or, like the WR802, has a unique static IP in the same subnet as the router but outside the router's DHCP pool.
TL-802N features
TL-802N Users Manual
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TL-WR902AC features
TL-WR902AC Users Manual