кажется проблема где то в iptables но не хватает ума понять где
# Generated by xtables-save v1.8.2 on Mon Dec 23 00:04:42 2019
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A FORWARD -i tun0 -j ACCEPT
-A FORWARD -i tun0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth0 -o tun0 -m state --state RELATED,ESTABLISHED -j ACCEPT
COMMIT
# Completed on Mon Dec 23 00:04:42 2019
# Generated by xtables-save v1.8.2 on Mon Dec 23 00:04:42 2019
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j SNAT --to-source Внешний_IP
COMMIT
# Completed on Mon Dec 23 00:04:42 2019
# sysctl net.ipv4.conf.all.forwarding
net.ipv4.conf.all.forwarding = 1
iptables -vn -L
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
ip route
default via 192.168.0.1 dev eth0 proto static metric 100
10.8.0.0/24 via 10.8.0.2 dev tun0
10.8.0.2 dev tun0 proto kernel scope link src 10.8.0.1
169.254.0.0/16 dev eth0 scope link metric 1000
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.20 metric 100