The Bank of Ireland said that their systems will get back online as the evening progresses.
ATMs are back online and the Banking 365 website and app services are being restored.
Some branches remain open until 8pm to welcome customers who were discommoded.
The bank apologised for the inconvenience.
The cause of the problems is still under investigation.
Previously, the bank had indicated that payments were being processed and that transactions at points of sale with credit and debit cards are going through.
A spokesman said the problem has nothing to do with the problems the bank encountered yesterday with its payment systems.
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