Can't get LACP to work on TrueNas Scale with TP-link SG3428X - hash algorithm?

[Christophe4TNAS]

Maybe there is someone here that can help this nood get LACP (802.3ad) set up between an TrueNas Scale device and a TP-link SG3428X switch.

I just got LACP set up with a Synology DS2419+ but on the TrueNas device (based on Asrock rack C2750D4i with 2 nics) I'm not getting there.

Several test changes have failed in applying a bond with the two nics.

What I'm still puzzled on is the correct hash algorithm on each side. The DS2419+ works fine with the default 'SRC MAC+DST MAC' on the switch side.

The SG3428X switch offers these possibilities:

On the TrueNas Scale device I try to put these nics in a bond:

After clicking add I entered following values:

Tried default LAYER2+3, then LAYER 2 and then LAYER3+4. LACPDU set to SLOW, haven't tried FAST yet.

On the switch side I stuck to the default 'SRC MAC+DST MAC'. Don't know which one is suitable for TrueNas. TP-link says following:

Hash Algorithm

Select the Hash Algorithm, based on which the switch can choose the port to forward the received packets. In this way, different data flows are forwarded on different physical links to implement load balancing. There are six options: SRC MAC: The computation is based on the source MAC addresses of the packets. DST MAC: The computation is based on the destination MAC addresses of the packets. SRC MAC+DST MAC: The computation is based on the source and destination MAC addresses of the packets. SRC IP: The computation is based on the source IP addresses of the packets. DST IP: The computation is based on the destination IP addresses of the packets. SRC IP+DST IP: The computation is based on the source and destination IP addresses of the packets.

I don't quite know where to go from here.
Help much appreciated, thanks
Christophe