This is not a console only issue as PC has had it also and it is a long issue they never cared to look into.
One post (or more) that had solutions by members was filled in the resolved section and there is like 4 or more threads for this.
Anyhow, i had this months ago and was over a month without being able to get in to download, support was non existent and i lost game time.
Had same issue when i switched to PS4 Pro so what i had done is assign a static IP address to my PS4, port forwarded, used different dns, changed MTU settings and used a VPN service.