Hello

Currently we have one RB493G with 3 WiFi midules and 90-degree antennas covering the entire island with 2,4Ghz internet. There are abount 15 users (households) using this service.
Now if I would like to upgrade to 5Ghz and higher speeds what would be the right products for that? I can't seem to find anything suitable for my needs from the routerboard family.

- Horizonal coverage needed is about 180-200 degrees (two 120 degree antennas?). Elavation is about 30m (top of lighthouse)
- We only have one ethernet cable to the top of the lighthouse where the device(s) need to be located
- We only have one public IP to work with

I like the specs of https://routerboard.com/RB921GS-5HPacD-19S but I do not want to do double NAT

Also there is a small possibility for that ethernet cable to be replaced with a singlemode fiber in the future. Currently there is a media converter at the base of the lighthouse converting it to copper and causing and unnecessary SPOF

You can run the mANT in "AP mode" , not using the the "router" in it, and just keep the RB493G as a router only.
I would use CAPSMAN on main router to manage the AP's.

Maybe something like this :
- one hEX PoE : you connect the ethernet (or fiber in the future, with the SFP) from the rest of the network, and it does the routing
- and two or three mANT (15s or 19s) : "just" serving as AP (no routing), and powered by POE by the hEX
This means : 3 devices to configure and monitor. But no external antenna to add/plug.

Or another idea : more like your current setup (only one card for all antenna) :
- one RB922UAGS-5HPacD : with a dual-chain AC controller integrated, SFP+eth
- one R11e-5HacD additionnal (mini pci-e) wireless card
- and 2 external antenna (TBD)

Or the same architecture, but with triple chain :
- one RB953GS-5HnT-RP : with a triple-chain AC controller integrated, SFP+eth
- one R11e-5HacT additionnal (mini pci-e) wireless card
- and 2 external antenna (TBD)
NB: this config has another mini pci-e slot for a third card+antenna if needed, and a second SFP (not sure how it can be usefull for you).

Or another idea : more like your current setup (only one card for all antenna) :
- one RB922UAGS-5HPacD : with a dual-chain AC controller integrated, SFP+eth
- one R11e-5HacD additionnal (mini pci-e) wireless card
- and 2 external antenna (TBD)

I like this idea! What would be the optimal (cost effective) CPE device for this? https://routerboard.com/RBSXT5HacD2n perhaps?

Or another idea : more like your current setup (only one card for all antenna) :
- one RB922UAGS-5HPacD : with a dual-chain AC controller integrated, SFP+eth
- one R11e-5HacD additionnal (mini pci-e) wireless card
- and 2 external antenna (TBD)

I like this idea!

Do you know which model of 5Ghz-antenna you are going to use ?
The mANT (15s or 19s) from Mikrotik ? Other brand ?

What would be the optimal (cost effective) CPE device for this? https://routerboard.com/RBSXT5HacD2n perhaps?

Yes, the SXT Lite5 ac is probably a good CPE device for you.

Yes, probably mANT