How to resend traffic further in the chain, i.e. tie client and server?

[OnkelTem]

Hi folks.

I need to tie both server and client in one config, so that all the traffic coming to the server would be sent further to another server.

This is my docker-compose.yml:

---
services:
  wireguard-server:
    image: lscr.io/linuxserver/wireguard:latest
    container_name: wireguard-server
    cap_add:
      - NET_ADMIN
      - SYS_MODULE #optional
    environment:
      - PUID=1000
      - PGID=1000
      - SERVERPORT=51820
      - PEERS=1
      - PEERDNS=auto
      - INTERNAL_SUBNET=10.10.10.0
      - ALLOWEDIPS=0.0.0.0/0
      - PERSISTENTKEEPALIVE_PEERS=
      - LOG_CONFS=true
    volumes:
      - ./server-config:/config
      - /lib/modules:/lib/modules #optional
    ports:
      - 51820:51820/udp
    sysctls:
      - net.ipv4.conf.all.src_valid_mark=1
      - net.ipv4.ip_forward=1
    restart: always
    networks:
      vpn-bridge:
        ipv4_address: 172.20.0.2

  wireguard-client:
    image: lscr.io/linuxserver/wireguard:latest
    container_name: wireguard-client
    cap_add:
      - NET_ADMIN
      - SYS_MODULE #optional
    environment:
      - PUID=1000
      - PGID=1000
      - SERVERPORT=51820
    volumes:
      - ./client-config:/config
      - /lib/modules:/lib/modules #optional
    sysctls:
      - net.ipv4.conf.all.src_valid_mark=1
    restart: always
    networks:
      vpn-bridge:
        ipv4_address: 172.20.0.3
    depends_on:
      - wireguard-server

networks:
  vpn-bridge:
    driver: bridge
    ipam:
      config:
        - subnet: 172.20.0.0/24

I successfully connect to the server, but the traffic is not forwarded further via client to another server. Which is not surprising as I haven't configured the routing.

The PostUp/Down section of server-config/wg_confs/wg0.conf are set by default to:

PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUT
ING -o eth+ -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTRO
UTING -o eth+ -j MASQUERADE

I'm not skilled in iproute2 and iptables, could you please point me in the right direction?

Thanks in advance!