Ensure you have TCP and UPD ports forwarding to the wireguard instances eth IP Address in your router/gateway

modinfo wireguard

dnf install wireguard-tools

net.ipv4.ip_forward = 1
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

firewall-cmd --add-port=15380/tcp
firewall-cmd --add-port=15380/udp
firewall-cmd --zone=public --add-masquerade

systemctl enable wg-quick@wg0.conf

If you want full-tunnel in your sites, change sites B, C and D configuration files:

AllowedIPs = 0.0.0.0/0

To route all traffic through wireguard tunnel in order to use site-A to reach internet