Welcome to HP Support Forums. 
I came across your post and would like to help.
I understand that you have an HP Officejet Pro 8615 e-All-in-One Printer and it disconnects often from the wireless network. I appreciate the steps you have performed and have certainly done a good job.
I would like to know if you have performed the steps that I suggested from my previous post in the same thread (assigning a manual IP address?
Also, our customer (CedarPrint) has fixed the issue by performing some additional steps. Here is the forums link for your perusal: http://hp.care/2t2Ub8W
Feel free to let me know. We will work this out together. Cheers!