Connecting to Cellular Internet and NMEA/AIS WiFi at the Same Time

Dual Cell and WiFi Connection


In many situations, users want their iPad to connect to sensors via WiFi while also accessing the internet via a cellular connection. This document describes various techniques that may be used to accomplish this.

A typical use scenario is the following. You are a professional pilot and use a WiFi based Pilot Plug or PPU to acquire AIS data and sensor information. However, you would also like to be able to access the internet while still connected to your plug.

There are several benefits to having an internet connection. First, you want to be able to use SEAiq AIS Sharing to access a global feed for AIS data. This allows you to view AIS targets that might be out of range of the AIS system on your current vessel. Second, you may wish to be online to access email or other internet resources such as web pages for tidal gauges, checking on your schedule, etc.

Problem Statement

The reason it is challenging to connect to both WiFi and cellular internet on an Apple iPad is that the iPad typically expect to only be connected to one network at a time, either via a WiFi or cellular connection. Because WiFi is typically faster, does not incur usage charges, and may use less power, it is usually preferred by the iPad over cellular connections. The normal behavior when an iPad has a cellular connection and it detects a WiFi connection, is to turn off the cellular connection and power down that part of the device. It will do this even if the WiFi connection does not connect to the general internet.

Please note that the reason why this can be difficult to set up has nothing to do with SEAiq. In fact, the security built-in to your iPad makes it so that SEAiq cannot make the configuration changes described in this document.

Manufacturers Supported Solutions

Below are manufacturers with documented solutions to this issue:


Please note that some of the settings here involve advanced network configuration. There is the possibility for your iPad, phone, and/or WiFi system to become misconfigured so they do not work normally. We will try to document how to fix such issues, but please be aware that by following these instructions you may have problems getting the settings back to work "normally."

Also, some of these settings may work in certain situations but not in others. They may be affected by the specific products being used, such as software versions, cellular internet carrier, etc.

Please send us an email to tell about your experiences with various approaches so that we can integrate your experience back into these instructions.

How You Can Help

When following these instructions and using the different approaches, please make a note of what you did and how things work. Please send us an email (SEAiq Settings / Send Us an Email) with any notes you have. In particular, we are interested in the following:

Typical Scenario

For the purposes of this document, we assume you are using a WiFi based Pilot Plug (such as those from PilotsTech) or a WiFi based PPU (such as those from Navicom Dynamics). We will refer to this as your Plug.

We also assume you have an cellular internet connection of some sort. This may be a direct one from your iPad. Or possibly indirectly via your cell phone which your iPad will access via tethering.

We also assume you have some familiarity with basic network configuration and know how to set up a simple WiFi connection to your Plug.

What is Tethering and What is a Personal Hotspot?

Tethering is a generic term for sharing a cellular internet connection from one device to another device that does not have a cellular connection. Apple iPads and iPhones use the term Personal Hotspot instead of tethering. The terms Personal Hotspot and tethering are used interchangeably in these instructions.

Tethering can be done using a cable or other wireless protocol such as Bluetooth or WiFi. In these instructions, we only use tethering via Bluetooth and WiFi.

In order to use tethering, you first need a device that has a cellular connection. In many cases that is enough. However, some cellular carriers do not enable the Personal Hotspot feature in the base data plans and require you to purchase an add-on plan. If you cannot find Personal Hotspot listed in your iPhone or iPad settings or if it is grayed out, you may need to talk to your provider about enabling that feature (if you want to use an option that requires it).

Option 1: Tethering From Your Phone

The first option we present involves accessing the internet by tethering via Blue-Tooth to your phone, which in this case we assume is an iPhone.

The advantage of this approach is that it may not involve as much complex configuration as other options, making it easier to set up. It also means you can use a WiFi-only iPad (without cellular data support) and you do not have to purchase a separate data plan for the iPad.

The disadvantage is that it requires you have a smart phone that supports Bluetooth tethering. For the purposes of these instructions, we assume you have an iPhone. You also must have a cellular data plan that allows you to tether an iPad to your phone. Not all cellular plans support this; some require purchasing a separate add-on capability to support this. A further disadvantage is that you have an additional device that you have to keep charged.

Note that on an iPhone, the tethering feature is called Personal Hotspot.



Restoring Your Configuration

When you are done, you may want to disable the Personal Hotspot feature on your phone.

Option 2: Tethering Your Plug From Your iPad

In this approach you will have your Plug tether to your iPad via WiFi. Your plug will not actually be accessing the internet via your iPad: the goal here is to trick your iPad into having both the WiFi and cellular connection running at the same time. Because it has a Plug tethered to it, it thinks that the cellular connection has to be left on so the Plug to access the internet.

An advantage of this approach is that you do not require a separate iPhone as in option 1. The main disadvantage is that it requires you to change the configuration of your Plug, which may require information from your manufacturer. If you make the changes to the Plug incorrectly, it may leave the Plug in an inoperable state.

Before attempting this configuration, check that you have complete documentation from your Plug manufacturer on how to get the Plug to connect to another WiFi network. This is the opposite of how Plugs normally work: normally, the Plug creates a WiFi network and the iPad connect to it.

This approach is not recommended for use with products from Navicom Dynamics.



Restoring Your Configuration

If you want to restore your Plug's configuration back to the default from the manufacturer, follow the instructions they (should) have provided you.

Option 3: Manually Configuring Your WiFi

In this approach you will manually configure your iPad WiFi connection so that it realizes the WiFi connection does not go to the internet and will therefore keep the cellular connection open.

We have had some positive and negative reports of this working. Please let us know whether or not you are successful.

This approach has the advantage of not requiring an extra device such as an iPhone or having to do special configuration for your Plug. You do not need a cellular connection that supports Personal Hotspot. However, you do need to carefully edit your iPad WiFi configuration. Note that after editing your WiFi configuration it may not be able to connect to normal networks without first switching it back to Automatic.



Restoring Your Configuration

When you are done using the configuration, go to the WiFi Network configuration and change the Manual setting(s) back to Automatic.