I try connect to internet via ps3 but the error code appear 80023121 pls advice

Unfortunately, the PSN is currently down due to "external intrusions". Sony is working around the clock to restore service to the PSN. Though there is no given timeframe, Sony said that the PSN should be back by next week.
This maintenance will eventually help improve the quality of PSN and improve its stability.
MORE INFO: Sony has updated its customers regarding the intrusion that happened on the PSN. Sony has verified that the intruder stole/got the personal information, usernames, emails, and passwords of PSN customers. However, the same cannot be said with regards to credit card information since it is stored in another part of the PSN and is highly secured/encrypted. It has also been verified by major credit card companies that no fraudulent/unauthorized activity has been caused by the PSN "break-in". A new system update would be introduced once the PSN is back up. This update would require all customers to change their passwords.

When did you try it. if you did so recently. Then you must know, that the sony PS3 network has been breached by some unknown viruses and people are not able to connect. Sony will respond to that soon. Sony also said that customers information has also been exposed to the unknown breacher.