Gmail incorrectly says my server's PTR record is wrong

[spamsam]

We have 2 shared cpanel server's that suddenly can send mail to and gmail account without getting rejected by google. We get the below message:

[email protected]
host gmail-smtp-in.l.google.com [142.250.27.27]
SMTP error from remote mail server after end of data:
550-5.7.25 [156.xxx.xxx.3] The IP address sending this message does not have a
550-5.7.25 PTR record setup, or the corresponding forward DNS entry does not
550-5.7.25 point to the sending IP. As a policy, Gmail does not accept messages
550-5.7.25 from IPs with missing PTR records. Please visit
550-5.7.25 https://support.google.com/mail/answer/81126#ip-practices for more
550 5.7.25 information. d26-20020a056402079a00b00457dbe73825si15450449edy.386 - gsmtp

And before anyoine says 'go check your PTR record bro', we have already tested and confirmed the following:
- PTR is correctly impelmented and resolving (both reverse and forward).
- SPF, DKIM, DMARC are all implemented.
- the ip is not listed under https://transparencyreport.google.com/safe-browsing/ (says no data)
- Mail volume has not increased.
- Cpanel support themselves said their is nothing wrong on the server.
- Server ip is not listed on any blacklist.
- We implement all googles best practices as per https://support.google.com/mail/answer/81126?hl=en
- Server does not send bulk mail.

Has any other experienced admins out there encountered this before? Because this seriously seems like an issue on googles end and contacting them directly, well, isn't exactly a feasible option.

 

[WAslayer]

There are two things to check here, the second being:

or the corresponding forward DNS entry does not point to the sending IP.

 

[cavedog]

There are two things to check here, the second being:

or the corresponding forward DNS entry does not point to the sending IP.

Or it could be that Google failed to lookup due to a network issue. Unlikely but could be an issue with the host network.

 

[spamsam]

Host network is Layer 2 in DC, already checked. It seems like the messages 'im getting back aren't consistent. It seemingly randomly fluctuates between the bounce message in the first post and the one below:

[email protected]
host gmail-smtp-in.l.google.com [142.250.27.27]
SMTP error from remote mail server after end of data:
550-5.7.26 This message does not pass authentication checks (SPF and DKIM both
550-5.7.26 do not pass). SPF check for [jnxxxx.co.za] does not pass with ip:
550-5.7.26 [156.xxx.xxx.3].To best protect our users from spam, the message has
550-5.7.26 been blocked. Please visit
550-5.7.26 https://support.google.com/mail/answer/81126#authentication for more
550 5.7.26 information. b20-20020a056402351400b00459a988ca2csi4660548edd.116 - gsmtp

Also, forward and reverse dns confirmed working

 

[WAslayer]

Looking like flakey DNS resolution, either caused by a network issue between Google and authoritative DNS server or issue on authoritative DNS server side..