Today October 21, it’s very difficult to sign in to the PlayStation Network. According to tweakers.net there was a very large DDoS attack against the Domain Name System service provider Dyn.
Not only is PlayStation Network having problems, also many websites and services like Spotify, Reddit, Github, Twitter, etc. are using Dyn DNS.
Quote from Bing:
“This attack is mainly impacting US East and is impacting Managed DNS customers in this region. Our Engineers are continuing to work on mitigating this issue.
Starting at 11:10 UTC on October 21th-Friday 2016 we began monitoring and mitigating a DDoS attack against our Dyn Managed DNS infrastructure. Some customers may experience increased DNS query latency and delayed zone propagation during this time. Updates will be posted as information becomes available.
Customers with questions or concerns are encouraged to reach out to our Technical Support Team.”
The problems mostly occour in the East Coast of the United States. You can check the status of Dyn on this website.
EDIT/ Problems should be sold by now.