Will such a network work?

Question

Network administration

I'm doing a re-planning of the network in the enterprise.
Two 100 Mbps ezernets are connected to the building to two routers (in the figure - in the red rectangle). An eight-port switch is connected to each of these two routers.
Routers and one file server are connected to both eight-port switches (ethernet sever in the picture). The three-digit router numbers are office space numbers. These routers, if necessary, can be changed to switches.
Each router in each office space has its own LAN clients and Wi-Fi clients.
It is necessary to make sure that any client in the 209th office, for example, can contact by IP and see any client in the 403rd office. Is it possible to do this by following the steps below? If not, or not completely correct, please correct or help.
They suggested splitting the DHCP pool of routers (in the red rectangle) in half, merging them (the question is - how? via ethernet to lan ports?), so that there is a common network, and breaking each pool into subnets with a /27 mask, assigning statics to each child router (which in office premises) and turn off NAT on each child router, turn on DHCP and restrict DHCP distribution within its own subnet.
One 100 Mbit cable is not enough for everyone, gigabit costs 10 times more (without exaggeration, the provider has a monopoly here) and it turns out that both need to be used.

Answer 1

1. You can put one head router, some Mikrotik, and turn on Internet channels through two interfaces. On it already and steer what traffic through which channel will go.
   
2. Each office has its own network - there is nothing wrong if there are a lot of clients there. If there are not very many clients, then you can shove them all into one / 16 network and let the head router issue DHCP addresses, and the simplest access points are in the offices.
   
3. If you decide to allocate a subnet to each office, but don’t want to bother with static routes, then there is such an option: if possible, then install simple microtics for offices, or OpenWRT-enabled routers and configure dynamic routing.
   

Answer 2

One 100 Mbit cable is not enough for everyone, gigabit costs 10 times more (without exaggeration, the provider has a monopoly here) and it turns out that both need to be used.

I didn’t understand why you can’t have a gigabit port connection with a bandwidth limit of up to 200 Mbps, for example. Or do they only require 10 times more for a port without a band?
The scheme with NAT (practically always - double) within the local network seems bright, extraordinary, difficult to maintain, unnecessarily complicated.

and turn off NAT on each child router

Yes, if the routers are office-home level (TP-LINK and others), then configure static routing.
UPD :

1. For a gigabit per month, they ask 10 times more. The company does not want to spend so much.

Again, I don't understand, sorry. Only for a gigabit port (with the same 100 Mbps bandwidth) are they asking ten times more? Check with your provider just in case, maybe they will give you 150-200 Mbps through a gigabit port for sane money.

2. At the expense of the scheme with NAT - I agree with you and will listen to suggestions with pleasure.

I support the proposals made by MrJeos . Unless I would leave DHCP only in offices, and address office routers statically. I also support mikrotik, they have a very affordable model (hAP lite). I would also advise you to analyze the current consumption before connecting the second channel. Perhaps it will be enough to simply redistribute the band by applying shaping / policing.

3. Yes - what? Will such a network work when taking into account the quote about the switched off nat?

Yes, it will, after a clear setting of addressing, static or dynamic routing. But be prepared for the fact that simultaneously using two channels of Internet access is a rather difficult task in terms of balancing. It may well turn out that everything is working now, and an hour later the consumer has utilized the lion's share of the channel, affecting the "Internet quality" of its neighbors in the channel, and at the same time, the neighboring channel is practically not loaded. This must be taken into account.

Answer 3

1. The scheme is strange, the link between switches or between routers is superfluous.
2. What equipment do you use? On the diagram, you need to sign the models of switches and routers, the range of possible solutions strongly depends on this.
3. What do they do for you that 100Mbit is not enough, do you have a maximum limit of 170 devices with such masks?
4. Why do you need to subnet everything? What are the requirements for routing?
5. Are the head routers linked via the Internet or locally?