Server LAN ping to client LAN fails

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On Asus Merlin router created two Wireguard VPN profiles for two travel routers; Asus ax57_Go and GLinet. Both profiles are almost identical with exception of different LAN IPs and tunnel IPs. Both client routers are in WISP mode. Both clients' LAN device can remote access the (VPN) server side PC, Internet and ping. However, server side devices ping fails to the remote Asus LAN devices. However, server side devices ping to remote GLinet LAN devices successful. Does anybody has success in setting up site-to-site Wireguard VPN with success in bi-directional ping? The server side LAN devices failed to ping the tunnel IP of the ax57_Go and its LAN IP as well.