I am having the same problem. I upgraded software on my 997si and 917, and on my friends 997si and 957. His works fine. I spent a lot of time troubleshooting with Humminbird and it was decided the interlink went bad on mine so they sent me another. It would start to merge, fail merge, and then say interlink disconnected. I borrowed my friend’s interlink and my set up works fine with it. Humminbird sent me a replacement interlink. Finally got it, pluged it in and the same thing happened. merge failed after about 15 seconds and interlink disconnect comes up. Hard to believe it is the 3rd interlink with this proble (2 of them brand new from humminbird) but my friend’s interlink works with his boat and my boat, and the hew ones won’t work with his set up or mine. I even tried deleting all waypoint data and reset to factory settings, (except it still has software upgraded) but got same results. I am still working with Humminbird to get resolved. It is VERY frustrating. I will post what happens. Oh by the way, systems work fine independantly with their own GPS antennas.