HCI_LE_WriteSuggestedDefaultDataLenCmd() can be used by the host (application) to suggest default values of txOctets and txTime to the controller. This function will write to the variable connInitialMaxTxTime.

When a connection is allocated, its value of connMaxTxTime is set to connInitialMaxTxTime. However, in the master or slave "connect" tasks are reset with connInitialMaxTxTimeUncoded or connInitialMaxTxTimeCoded depending on the initiating PHY.

However, there is no way for the customer to influence the values of connInitialMaxTxTimeUncoded  or connInitialMaxTxTimeCoded  from the application.

From the spec ([Vol 6] Part B, Section 4.5.10):

"connInitialMaxTxTimeCoded - the value of connMaxTxTime that the
Controller will use for a new connection on the LE Coded PHY. The value of connInitialMaxTxTimeCoded shall be the greater of 2704 and the value of connInitialMaxTxTime."

Steps to re-create problem:

1. Call HCI_LE_WriteSuggestedDefaultDataLenCmd from application with non default values. e.g. txOctets = 68 and txTime = 6000.
2. Connect to SBP
3. Observe the LL_LENGTH_REQ/RSP do not contain txTime as indicated by default value