Methods and devices are disclosed for dynamically fragmenting packets transmitted in a communications network. Fragments are generated by splitting a packet based on a value of a fragment size parameter. A first fragment is sent to a receiving node. As the sending node, a transmission success parameter is determined that indicates whether the first fragment was successfully received. Based on the value of the transmission success parameter, a link quality parameter value representing a chance a second fragment having the same size as the first fragment will be successfully received by the receiving node is updated. The sending node compares the value of the link quality parameter and a value of a quality threshold parameter and changes the value of the fragment size parameter based on a result of the comparison.