I purchased a 3 Year NordVPN service only a few months ago, I've now just bought a brand new TP-Link Archer MR200 router which is V3 from what I understand.
Now although it's OpenVPN, I'm told you cannot use it with NordVPN as it's not native.
I bought this router on the basis it was 4g and it had OpenVPN, I should of just got a basic one now.
Can I install OpenWRT on this? or should I get another VPN service?
You might want to consider the GL.iNet X750 "Spitz" as a suitable device for all-in-one support of 4G (CAT6 available), OpenVPN and wireless. Recent, "close to the tree" OpenWrt with packages and OEM GUI in addition to LuCI installed and supported by the OEM (frequent builds as well). I have the AR750S and AR300M-Lite and am impressed with the engineering, build quality, and support.
1 x WAN Ethernet port
1 x LAN Ethernet port
1 x USB 2.0 port
1 x micro SIM card slot
1 x MicroSD card slot
CPU QCA9531@650MHz
Memory / Storage DDR2 128MB / FLASH 16MB
3G/4G Mini PCIe Module Support CAT4/CAT6 Mini PCIe
4G LTE Antennas 2 x detachable external antennas
Wi-Fi Antennas 2dBi 5G & 2.4G internal antennas
Protocol 802.11 b/g/n/ac
Wi-Fi Speed 2.4GHz(300Mbps), 5GHz(433Mbps)
TX power 2.4GHz: 20dBm (11b) Max, 5GHz: 20dBm (11a) Max