Mails not getting delivered to the New Exchange Server 2016 in an environment

Hi All, 

We have introduced a new exchange server 2016, which will soon be replacing the existing Exchnage server 2013. It is an Hybrid environment where we have Office 365, Exchange 2013 and Exchange 2016 in coexistance.

Any email that is being sent from Exchange Online to the Mailbox that exists on Exchange Server 2016 it first gets deliver to Exchange 2013 and then to Exchange 2016, but when we send an email directly to the new exchange server 2016 it gives us the error message "450 4.4.317 Cannot connect to remote server". We did checked the Load Balancer logs in an environment and found that the email did land up in an environement and connects to the VIP of Load Balancer but it dosen't go forward to the exchange 2016. 

Connector Validation is also getting failed on the exchange admin portal, when we validated with the email ID that exists on Exchange server 2016.

Can any one suggest what else I should check and also tell me what could be the reason for this error message.

Thanks.