So unfortunately regenerating the certificates didn't help 
What settings did you use to generate yours? This is how I did it.
CA:
ipsec pki --gen --type rsa --size 4096 --outform pem > ca/ikev2CA.key ipsec pki --self --ca --lifetime 3650 --in ca/ikev2CA.key --type rsa --dn "C=My, O=Custom, CN=IKEv2 CA" --outform pem > ca/ikev2CA.cer
VPN GW:
ipsec pki --gen --type rsa --size 2048 --outform pem > private/vpngw.key ipsec pki --pub --in private/vpngw.key --type rsa | ipsec pki --issue --lifetime 730 --cacert ca/ikev2CA.cer --cakey ca/ikev2CA.key --dn "C=My, O=Custom, CN=IKEv2 GW" --san vpngw.domain.tld --san PUBLIC_IP --san @PUBLIC_IP --flag serverAuth --flag ikeIntermediate --outform pem > certs/vpngw.cer
Client:
ipsec pki --gen --type rsa --size 2048 --outform pem > private/client.key ipsec pki --pub --in private/client.key --type rsa | ipsec pki --issue --lifetime 730 --cacert ca/ikev2CA.cer --cakey ca/ikev2CA.key --dn "C=My, O=Custom, CN=IKEv2 Client" --san "client.domain.internal" --outform pem > certs/client.cer