I second this. I have a similar setup and use it extensivly at anchor for my work. I am a network engineer that designs networks remotely. The key is to mount your ariel high up and clear of any close metal (as best you can of course)Previously I have just been using a bog standard domestic 4G router and a cheaper, smaller antenna. If your boat electronics locker is getting wet enough to break stuff like that industrial router you have bigger issues than internet access.
Oh, wrong links. This antenna: Poynting High Performance 6.2dB 2x2 MIMO Omni LTE/4G/WiFi Antenna (PO-OMNI-600) , will be mounted on my radar mast. And this router Teltonika RUT950 4G LTE WLAN Router
I use an app called Mastdata that shows you the locations of the masts. It helps you to work out where you are likely to get a good signal.