I haven't tried any of the speedfusion stuff yet (haven't felt the need). The Transit is handling the on-boat wifi. As far as failover, the Groove is plugged into the WAN port of the Transit (set as priority 1 on the Transit), then cellular is priority 2. Failover works nicely. Takes a couple seconds for the Transit to notice the loss of internet from the Groove, then fails over to cellular. Fail-back is almost seamless. I settled on health check every 5 seconds for the WAN port, timeout after 3 seconds, failover after 1 failure (5 successes needed to fail back).
Your proposed setup is the better way to do it. Keeps all of the config in 1 interface instead of 2, plus the Transit has 2x2 wifi, the Groove is 1x1 (and doesn't auto switch between 2.4 and 5ghz while the Transit can for wifi WAN).
I may eventually add a separate access point and move to using the wifi WAN feature on the Transit, but I avoided it initially. The Groove (with antenna) and a nice mount for it cost me $150 which is significantly less than a good external antenna setup for the Transit and then a separate access point for the on-boat wifi. So the Groove is just a product of me being cheap for the initial setup.
My concern about interfaces is that while I know
how to do all the technical stuff, I really want to avoid having to fire up overly technical interfaces (text terminal screens, etc) any time we anchor somewhere that might have available wifi.
The Groove is probably a workable solution for a friend that has a new-to-them boat that came with a MOFI4500 unit. The WiFi radio in the MOFI is slow, 2.4 only and not all that great. Adding a Groove might give him the on-shore WiFi bridging he's after. Being able to wire it with just PoE is a plus, as that's just one twisted pair line up the mast.
I have other Ubiquiti stuff on-board for the on-boat WiFi. So if I had to add a WiFi bridge like this I'd probably get the Bullet, if just to use the same configuration apps. But for stand-alone, the Mikrotik might be better, as the Unifi stuff tends to have features that expect you to have all Unifi stuff (like their switches/router).
I'm cautiously optimistic the Peplink will be able to handle both cell and shore wifi (with suitable antennas added, of course). But if not I can always add a Groove/Bullet.
I went with separate WiFi access points because where the router is best placed is not the best place for providing WiFi. Using separate access points lets you just run a twisted pair wire with Power-over-Ethernet and place them wherever gives best WiFi coverage on the boat.
It does add the complexity of an added network switch and the PoE power adapting. But that's an OK trade-off. There are such things are PoE switches that'll do both, but finding one that does the right PoE voltage narrows your selections a lot. It's gives you more options if you get a regular Ethernet switch and then whatever separate PoE adapters are needed. It's a few more devices and some wiring, but the cost is minimal and you avoid getting stuck later if you want to change or user different PoE devices (like cameras).
