Data link issue

Dear All

    In one of our application i am using the datalink , to connect from OPTO to database till now its working fine, sometimes data link getting hanged upto around 8 to 10 hours,before 8Hours from this situation started i tried number of times to restart the service ,after restart it is showing link is running but actual data not transferring.after 10hours one onetime service restart its started working. kindly guide me why this happening, here is the attachment of data link error screen shots for your reference..