Firewall. Currently running a Zyxel, and you don't seem to have FW so I might continue with that
List of basic functionality.
- Router > Rack mounted with PoE, 1 WAN and 4-5 PoE ports. No WiFi.
- Switch 1 > Rack mounted and 48 ports .
- Switch 2 > Rack mounted and 24 ports
- AP > Dual Band and high speed.
You left one important thing out: speed.
What is the needed routing speed?
What is the internet link speed?
What is the interconnection needed speed, between the switches? I imagine that the 48 and 24 ports switches would connect to different subnets, on different router ports. Am I right?
As Jack the Ripper used to say, lets do it by parts.
Router:
The only router I found with 4 PoE ethernet ports is the
https://mikrotik.com/product/RB960PGS-PB. But its routing capabilities are very weak. One possibility would be to just buy some PoE injectors and use a "normal" router. Another would be to buy a cheap 5 port switch (
https://mikrotik.com/product/RB260GSP) with PASSIVE PoE on 4 ports. Yet another would be to drop the requirement. Or, of course, You could buy another brand.
Dropping the PoE requirement for the router make easier to find it: Mikrotik sells from small itsy bitsy routers to monsters like the CCR1076. One of them will (probably) be the right one for You.
Switch with PoE (RouterOS):
24 gigabit PoE ports and 4 SFP+ ports:
https://mikrotik.com/product/crs328_24p_4s_rm
48 gigabit PoE ports, 4 SFP+ ports and 2 QSFP+ ports:
https://mikrotik.com/product/crs354_48p_4s_2q_rm
Switch without PoE (RouterOS):
24 gigabit ports and 2 SFP+ ports:
https://mikrotik.com/product/CRS326-24G-2SplusRM
48 gigabit ports, 4 SFP+ ports and 2 QSFP+ ports:
https://mikrotik.com/product/crs354_48g_4splus2qplusrm
AP dual band high speed:
Here I'm not sure.
-- EDIT --
Sorry, not dual or quadruple band. Dual or quadruple CHAINS.
-- /EDIT --
We have several modern devices with dual band, and one modern device with quadruple band and 3 radios (one 2,4 and two 5GHz). All of them can be used as AP. Some of them can be used as routers as well. I don't know how well (or how bad) they perform. Better to ask someone here used to them.
https://mikrotik.com/product/wap_ac
https://mikrotik.com/product/hap_ac2
https://mikrotik.com/product/hap_ac3
https://mikrotik.com/product/audience