Winsock error for send-connector

Hello,

Recently we have configured our outbound mail to route via Exchange 365. We have set-up a new send-connector and all is working fine. But in the send-logs I see an error:

Failed to connect. Winsock error code: 10051, Win32 error code: 10051, Destination domain: [tenantname].mx.microsoft, Error Message: A socket operation was attempted to an unreachable network [IPv6-address]:25.

It looks like that some goes wrong with the communication to Exchange 365 over IPv6. After 4 attemps the connection switches to IPv4 and the mail is send to Office 365.
I think the firewall is blocking IPv6, is it possible to disable IPv6? And is it wise to do that?

What are your thoughts about that?

Kind regards,
Arjan