I have been having problems with networking a 1198c SI and 998c HD SI. The 1198 had the ethernet pull down menu when I bought it used a few weeks back. The 998 has never had the ethernet pull down menu. I bought a brand new ethernet cable from BPS and connected the two units. They would not communicate, checked the Humminbird website and it was recommended that both units have the same software version. I updated the software on both to 7.670. After the update the 1198 lost the ethernet pull down menu. Tried factory default rests on both units with no results.

Took both units to BPS and went through the software and ethernet connection with the top guy in marine electronics. Tried older versions of the software, tried a different new cable off the shelf with no results. The chances of having a bad cable has been ruled out. I really think the possibility of have two units with defective ethernet ports is very slim. The man at BPS is working with tech support at Humminbird on this problem. They have not been able to find a solution.

The crazy part is, they will communicate and share GPS antenna, weather sense data, plus way-points thru the old Inter link on my boat. The units will not recognize an ethernet cable when connected.

Note - The inter link was disconnected when the ehternet was connected.

Does anyone have any ideas?

Do both units display an IP address, I believe it should be on the system status screen

No they do not. They show a Mac address.