I would need to see the PHD2 debug log. The log will show the messages PHD2 received from SGP and the responses it sent back.
I do not think the message PHD2 - No messages received from PHD2 for 1 minute, checking socket with status... necessarily indicates any problem with the PHD2-SGP communication. PHD2 does not send guide frame updates when guiding is stopped. If SGP tells PHD2 to stop guiding so SGP can do something like centering an object, then PHD2 has no updates to send to SGP and SGP logs the message about not getting any updates.
Andy