Setup:

ubuntu server 18.04 with squid installed and working
--> installed openvpn client on ubuntu server


raspberry pi in my home network with openvpn server installed and working (can connect and use connection with any device)


objective:
"anydevice" using HTTP proxy --> external server with squid proxy (openvpn client) ---> RPi (openvpn server with dyn.dns public address) ---> using home internet connection

problem:

if i connect to the squid proxy i can use it and everything works fine... as soon as i establish the openvpn connection the traffic from "anydevice" isn't routed through the openvpn connection or at least i get a timeout error

routing table without openvpn established

route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 172.xx.yy.1 0.0.0.0 UG 100 0 0 eth0
172.xx.yy.0 0.0.0.0 255.255.240.0 U 0 0 0 eth0
172.xx.yy.1 0.0.0.0 255.255.255.255 UH 100 0 0 eth0

if futher input is need i will provide asap
thanks