How to connect vpn site to site from a remote client?

[jaylee]

Hello I am jay. I need your help with vpn configuration.
I want to configure the vpn between various branches.
I have two questions.

1. I want to connect to a remote client in addition to site to site so that vpn communication can be made between all branches.
2. I have a question about how to assign IP to the vpn tunnel interface.

The VPN configuration is as follows:
It is now a test environment. It will be used when the test is completed.

Main Office
Wan IP 192.168.10.5/24
Lan IP 192.168.20.1/24
Tunnel IP 10.0.0.1/24

B Office
Wan IP 192.168.10.7
Lan IP 30.0.0.1
Tunnel IP 10.0.0.2/24

First question:
In the ideal situation, the main office and the B office
VPN is connected and there is no communication problem.
In this situation, I want to connect to vpn as a remote client.
I set up the Remote Client VPN on the main office VPN server and communicated well with the main office 192.168.20.1/24 band.
However, there is no communication with the B SIte Vpn 30.0.0.1/24 band. How can I resolve this issue?

P.S In the second question, the problem with ip allocation was to get an ip with a different subnet. In this environment, there is no problem connecting the vpn.

second question:
There is a problem with how to allocate the IP of the vpn tunnel section.
If Tunnel IP is set to 10.0.0.0/24, 10.0.0.1 is assigned to the main office and 10.0.0.2 is assigned to the B office.
In this situation, if the remote client tries to connect, it will get IP 10.0.0.2.
This will cause problems with VPN communication. Is there a way to manually assign the tunnel interval IP? In other posts, I saw how to enter a subnet of 30.
Should this be done in this way?
If so, is routing processing not required?

I need a lot of help from you. I am looking forward to your kind reply. Thank you very much.