@Raphyraphy 

try change ip pool like this 

MODEM: 192.168.200.1

LAN-RUTER: 192.168.210.1/24

VPN SERVER IP POOL: 10.23.1.10 - 10.23.1.100

ROUTER VPN-KLIENT: 192.168.113.1

SERVER prøver å få tilgang til: 10.101.1.25

Hello @MR.S , thanks for your help again :)

I try change ip pool like this

But not working, same problem

  @Raphyraphy 

how is the configuration between modem and router? do you have port forwarded ssl vpn port? there is little information about your solution,

  @MR.S 

I tried to make a diagram of the network, with under each device the configuration information that seems important to me, I hope this will help.

As a reminder, everything works fine, the only thing that does not work is accessing a server with the IP 10.101.1.25 which is on the "OpenVPN Client" when connected to the "SSL VPN Server".

  @Raphyraphy 

Is the OpenVPN client on the same router as the SSL VPN Server or is the client on a PC? and where is 10.101.1.25 in your diagram? I don't quite understand what you are trying to achieve here, to me it looks like you have two components, a Client and an SSL Server, if you are going to connect the client to the SSL Server, the most common thing is to do it from WAN to LAN, a client on Router normally connects from LAN to WAN, maybe @Clive_A  better understands what you are trying to do.

  @Clive_A @MR.S 

Thank you for your help, sorry I am well aware that my diagram is not a "professional" diagram, here is a new version which I hope will be clearer, I removed what seemed not useful for this specific problem, and added the missing equipment.

So to answer the question, yes the OpenVPN client is on the same router as the SSL VPN server, and the 10.101.1.25 server is located after the VPN tunnel of the VPN client (To be honest I don't have access to the exact configuration that is beyond the VPN client, I "guessed" it from the tracert, where we see that it connects to 192.168.113.1, then 10.102.1.1, and finally the 10.101.1.25 server)

I added the red and green lines so you can see where my problem is and different ping test that I did, so from a PC connected directly to my router, I can access the 10.101.1.25 server which is beyond the VPN client, however from a PC connected to my VPN server, impossible to access it.

Thanks.

  @Clive_A 

In addition to my answer just above, here is the routing table of my router 192.168.200.254, the one that contains pretty much everything, my vlans, my VPN client and my VPN server.

  @Raphyraphy 

I don't know if it works, you connect to the router with SSL VPN from a client and proceed with OpenVPN on the same router, is that correct? I think you have to contact TP-Link support to ask them to help you, they may be able to run a remote to look at your setup. Clive_A is on the thread, maybe he has some tips. Unfortunately, I can't help you with good advice when I know so little. 

  @Raphyraphy 

I did a test here, an ER707-M2 with SSL VPN server and the same router has an OpenVPN client for some remote networks. when I connect to the SSL VPN with my PC, I only get the local networks on the ER707, I don't know how to route from the SSL VPN to the OpenVPN client on the same router. so I can't connect to any of the networks that go in the OpenVPN client on the router. I use a full tunnel so all traffic from my PC goes out on the ER707 LAN and WAN but not OpenVPN.