Is there any way to connect to Wireguard behind a Carrier-grade NAT? I have
a backup LTE connection, without proper public ip + I have a home server
with Wireguard.

SIDE_A = LTE connection, without public IP, NAT
SIDE_A_SERVER = WIREGUARD (connecting to sideb.dyndns.org)

SIDE_B = VDSL with public ip + ddns (sideb.dyndns.org)
SIDE_B_SERVER = WIREGUARD (cannot connect to SIDE_A, no public ip)

Best regards,
Adrian