network architecture

Firstly I would say hi to all You guys.

I stand before recreation of small wireless network and I would like to get advice from all of You.
The topology of the network:
I have 5 buildings and in each of them there is a switch with wired users connected to.
In shortcut there is wireless RB on roof ← wired switch ← wired users.
The main RB will get data from each building (and from themselve) and pass to RB which is connected to ISP (5km far away from network).
I know this post sounds noobie but there is no other way to explain what I would like to do.

Now network works on WDS and one of RB is bridge to RB ISP.
Because there is to big delay in network I need to do this in other way so I thought about PPPoE.
On each building will be PPPoE client, and one of them will work as PPPoE client and server to get data from buildings and pass to RB ISP where would be PPPoE server. I don’t know if this is clever so please comment and advice.
Thanks in advance!

P.S. I use RB411.

Have you considered NOT doing a bridged network but using routing, together with MPLS etc. for ethernet pass through / vlans should that be needed?

The setup of the backbone and the whole configuration as beridget (if I undersatand this right) wounds like a little nightmare. I would use a normal switching approach per building, routing subnets via MPLS through dedicated links on top (i.e. point to point, not a mesh type architeture).

I’ll suggest you route between the buildings , this will increase effeciency of the network, by reducing Broadcast to each building,

Building A could use the 192.168.1.0/24 ip range
users 1 in Building A will used this configuration
Ip address 192.168.1.3
Gateway 192.168.1.1 (ip address on the Rb)
DNs 192.168.1.1

Building B could use the 192.168.2.0/24 ip range
users 1 in Building B will used this configuration
Ip address 192.168.2.3
Gateway 192.168.2.1 (ip address on the Rb)
DNs 192.168.2.1

A routing protocol or static routing should be configured on all the Rbs.

r the RB’s talking to each other using WDS or u have dedicated ptp links for connecting the buildings. How far apart r the buildings?