The Yacht Router Micro from Locomarine is over 1000€ but promises to connect to wifis and GSM.
Digital Yacht offers routers with high gain Wifi antenna and GSM module.
The Yachtrouter 2 from B.I.S. promises connectivity to harbour Wifis and has two GSM modules.
The Red Box by Mailasail connects over Lan, 3G plus sattelite. The distant Wifi is connected via the Lan interface as already described.
This blog has no tests for these devices so far. Please provide some information if you have any.