By Tanner Pierce. Published Apr 17, 2017. Sony has announced they will be shutting down the servers for a few PlayStation 3 era games, as well as one PlayStation Vita game, and one PlayStation 4
This is by far the most common cause of the type of problem you are having. There are several other things that could be causing it as well. It's possible (especially if your console is getting older) that you need to replace the thermal paste and give the heat sink a good cleaning. This is a fairly common cause of PS4's overheating as well.
Playstation 3 servers are shutting down forever on june 3rd 2021. This is what the post looked like on Instagram at the time of writing: (Source: Instagram screenshot taken on Mon May 10 20:50:20 UTC) Lead Stories could not find publicly available evidence that all PS3 servers would be shutting down. According to the online PS3 User's Guide
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