Communication issue with S7-300

Hello,

I need to read from and write to a specific DB on an S7-300 PLC.

I set up the connection using the S7-300 driver. I can read the tags, but I cannot write to them.
There are no errors in the Gateway logs, so I suspect the issue may be on the PLC side.

I'm not very familiar with Siemens PLCs. Is there a specific parameter or setting that needs to be changed to allow writing?