Thanks for the tips. this is the whole story:
I have openwrt 19.07.1 installed on my device (TP-Link TD-W8970). I using my device as Modem/Router & AccessPoint. I connect to the Internet using DSL Line (PPPoE protocol) using this device. To bypass Net restrections and Net blocking, I had to use one of the VPN solutions on my PC/Laptop/Mobile phone and etc... this is why I want to use a VPN server. Last year I tried to setup openvpn directly on my openwrt, so when I connected to my Modem, I don't need enable VPN on my Phone or Laptop. you can see my last year topic here
I just wanna do the same thing as I done last year, this time using wireguard protocol: My 8970 connect to the WAN (Internet) Using DSL and I access to the internet by connecting to the 'wifi1'. now I want to setup a wireguard client on my 8970 and share tunneled connection as a new network/wifi named 'wifi2'. that's it.