This is gonna be long winded so please bear with me. tldr at bottom.
Having the same name makes a simple user experience.
Having multiple different names makes troubleshooting and finding issues easier; I am a big fan of this approach as you gain a lot while sacrificing very little. I shall explain why. I was a phone rep and network technician for a year and had to do trouble shooting and we had sites with homogeneous or unique wifi SSID's.
Consider these two scenarios; customer has issues streaming a youtube video in the shop.
Scenario 1, Homogeneous SSID
If we went with the monolithic wifi name, then we need to answer quite a few variables and ask questions the customer probably doesn't know.
Q: What's your IP address?
This can be difficult to find, as it is obfuscated on mobile devices sometimes. Also, people don't know what the hell you are asking when you ask this 9/10.
S: A possible solution is If you subnet the AP's it will help you figure out which one they are on. Just find their IP address and have a reference sheet to which ap has what subnet. This looses effectiveness and creates more problems though for two reasons.
- As you just added a second NAT wall with adds latency and overhead to your main router and AP's. Suppose a client wants to communicate with someone on the network, who is on a different subnet, over a webapp. Now, it has added many more cycles to get the same thing done had it just been on the same subnet. This could lead to a bad user experience.
Q: What's your location in the shop?
If customer was in the center-ish area of the shop, this makes things more difficult that if he was in one of the corners where it would be more obvious which AP he might be on. Folks in the corners will have a better experience than folks in the middle, as there is now a problem of the layout of the AP's relative to each other, and the checking to make sure none of the bands overlap and cause interference. The customer is this situation could have access to several AP's at relative strengths and constantly switch and cause frustration.
Q: what is the amount of customers the shop can handle? Now I know its a small shop so it probably won't exhaust a subnet of /24 (254 nodes), but on large networks (business/coporate), this is a real concern. And when you want a network with more than 254 nodes your need to rely of subnetting even more so, so the previous approach of just separating everything on different subnets fails here because usually we would all devices of type x on subnet y for security reasons, or something of that nature. Prints all go on subnet z and have not WAN access, POS systems on a heavily restricted network, etc.
All the while this is going on, a depth of knowledge is needed to even try to begin how to solve the problem; and we're just getting started.
Scenario 2, Unique SSID
You break up all the access points with different SSID's.
Q: which wifi are you connected to?
A: I am connected to this wifi.
You can immediately begin troubleshooting that AP to see if its a problem, and or their connection. You can get straight to brass tacks from the start.
You can easily implement different security's on different AP's; if you so choose. You could do this with the previous method, but it would get confusing very fast if you did not have a working knowledge of how exactly the network was set up.
If you happen to have to have an issue, on a network, large network (40+ AP's), not familiar with the network, and it all goes by one name, trouble shooting becomes more complicated and lengthier, where as the unique SSID method establishes where the issue is happening in just one question.
Now this method is not perfect, it still has the NAT issue. But in terms of complexity it is quite trivial to just run the default setup page on the AP's and give them different names; its not complicated at all.
One large network appropriate to expected client size. A standard /24 network will suffice most of the time, but sometimes it needs to be bigger.
Have one central main DHCP server, which handles all the NAT, and all the AP's do not run their own DHCP but inherit, adn you break up which AP's get which name; based on physical location, and then split them futher onto different VLANs. This way everything is one one single network, but has different security for each VLAN.
With a core DHCP server managing the network, with location based SSID's for AP's, each on specific VLANS, you can have performance and security in one package, the only trade off is that this can be the most complicated, but you get the most benefits, troubling-shooting ease, and security.