Looks like the APN certificate expired two days ago:
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, O=Apple Inc., OU=Apple Worldwide Developer Relations, CN=Apple Worldwide Developer Relations Certification Authority
Validity
Not Before: Apr 16 16:08:11 2017 GMT
Not After : May 16 16:08:11 2018 GMT
Fixed / renewed.
I'll notice it quicker if pinged on the app support thread. Cheers

Thanks for the fix.