I am trying to put together a 'core' for a plastic surgeon/family friend. He has been burned by 'pros'. His recent network has (based on some quick pictures that were sent to me, I plan to visit the site and do a more through dive into the network):

Netgear device with only it's WAN port plugged in (4 LAN ports empty). Not sure what this is doing and if it's a wifi device. It does have an empty USB on the back. Closest thing so far I could find was an N900 router that looks like it.

Luxal AC300 (WXR-3000 or 3150). There only known WiFi device. After the first patient room out of about 8, there is no WiFi. It sits on top of three Sonos Amps. Not sure if they are connected to the Luxal.

TrendNet TEG-S16g with only 2 ports connected/active.

3Com OfficeConnect 16 with 5 devices active (didn't get a picture if more are connected) (3 1G and 2 100MB).

Patch panel with 9 connections.

All the rooms have a drop in them.

Outside of the WiFi being bad, they also have almost no cellular service inside the office and their ISP connection in that whole building is unreliable and they have dropouts many times a day.

As far as I can tell this is just a total flat network, I don't think any of the above devices are L3 capable.

This may be overkill, but this is the way I have done my installs (I work at the mid to usually larger/Enterprise level)

My plan is to find out what their provider is then if it's Comcast or ATT figure out why it's so spotty and if not buy a Comcast and ATT circuit with at least 1 static IP. I'd like to run each circuit to a pair of switches and then each switch to a pair of firewalls in HA. That way they can lose any one device and at least be partially in business (mostly loss of connectivity if a switch dies). This may be overkill and maybe losing the second firewall more cost-effective, I'd still like to stack just from the easier management.

I am debating Meraki vs Fortinet. I don't have a lot of experience with MXs, I do have a lot of experience with Fortigates. I don't have any experience with Fortiswitches, but I have a lot of experience with MS and Meraki stacking. They do need POE. I have a lot of experience with Meraki MR access points and none with Fortinet's.

What I think would be my best option is Fortinet firewall(s) and Meraki MS and MR behind them. Probably a 60F if Fortinet and MX75? if Meraki (assuming he is using 1G circuits, he sent a speedtest of 400Mbps from his phone). I am also open to Cisco AP's (and run Mobility Express) and switches, maybe scoring a pair of 2960X or 3850's as they have some continued support for the next few years and will still at least work after that period.

He has another two practices, but those perform well according to him. After this I plan to look at his phone system, there are 3 Arris boxes and an NEC device running it. They only have about a half dozen phones in that office so I don't know what is going on there.

To top it off "his guy", installed a 'new' server last year or so. It's a Dell Optiplex 7020 tower from 2015! He is not sure what it does (it was powered on though). This is definitely another thing to update.