HI and welcome to the forum.
Data Connections are verified on form open, even if they are not being queried so i think it is difficult to remove this other than coding it completly which would add more complexity and hassle to the form.
Have you thought about putting the DB in a network folder, probably already is, but then set it up as a off-line folder? This way the laptop will still see it even though it is off-line and you will not have the error.
This would also enable you to not have to start the form before they leave the office. They would take the latest copy with them and could access it while off-line.
You still have to manage the submit and the sync but if you want to email me, we could discuss what I have seen before.