mjhjmtu

OpenVPN opens tun device, but does not up this, therefore can't add the route afterwards.
This command does not up the device

/sbin/ifconfig tun0 172.31.0.6 pointopoint 172.31.0.5 mtu 1500

It works fine, if I up the device manually by ip link command or

 ifconfig tun0 up

But then I need to add all routes by myself. How can I get running without manually tasks?
Here is my client conf. The same conf works fine on windows. I appreciate for any help

dev tun 
proto tcp 
remote x.x.x.x 1194 
cipher AES-128-CBC 
auth SHA1 
resolv-retry infinite 
nobind 
persist-key 
persist-tun 
client 
auth-user-pass 
verb 3

Here is my log:

Tue Aug 7 11:25:00 2018 WARNING: No server certificate verification method has been enabled. See http://openvpn.net/howto.html#mitm for more info. 
Tue Aug 7 11:25:00 2018 TCP/UDP: Preserving recently used remote address: [AF_INET]x.x.x.x:1194 
Tue Aug 7 11:25:00 2018 Socket Buffers: R=[87380->87380] S=[16384->16384] 
Tue Aug 7 11:25:00 2018 Attempting to establish TCP connection with [AF_INET]x.x.x.x:1194 [nonblock] 
Tue Aug 7 11:25:01 2018 TCP connection established with [AF_INET]x.x.x.x:1194 
Tue Aug 7 11:25:01 2018 TCP_CLIENT link local: (not bound) 
Tue Aug 7 11:25:01 2018 TCP_CLIENT link remote: [AF_INET]x.x.x.x:1194 
Tue Aug 7 11:25:01 2018 TLS: Initial packet from [AF_INET]x.x.x.x:1194, sid=8188f10d 67197c08 
Tue Aug 7 11:25:01 2018 WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this 
Tue Aug 7 11:25:01 2018 VERIFY OK: depth=1, C=DE, O=xx, CN=x.x.x.x 
Tue Aug 7 11:25:01 2018 VERIFY OK: depth=0, C=DE, O=xx, CN=x.x.x.x 
Tue Aug 7 11:25:01 2018 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA 
Tue Aug 7 11:25:01 2018 [x.x.x.x] Peer Connection Initiated with [AF_INET]x.x.x.x:1194 
Tue Aug 7 11:25:03 2018 SENT CONTROL [x.x.x.x]: 'PUSH_REQUEST' (status=1) 
Tue Aug 7 11:25:03 2018 PUSH: Received control message: 'PUSH_REPLY,route 192.168.1.0 255.255.255.0,route 172.31.0.0 255.255.255.0,topology net30,ping 10,ping-restart 120,ifconfig 172.31.0.6 172.31.0.5' 
Tue Aug 7 11:25:03 2018 OPTIONS IMPORT: timers and/or timeouts modified 
Tue Aug 7 11:25:03 2018 OPTIONS IMPORT: --ifconfig/up options modified 
Tue Aug 7 11:25:03 2018 OPTIONS IMPORT: route options modified 
Tue Aug 7 11:25:03 2018 Outgoing Data Channel: Cipher 'AES-128-CBC' initialized with 128 bit key 
Tue Aug 7 11:25:03 2018 Outgoing Data Channel: Using 160 bit message hash 'SHA1' for HMAC authentication 
Tue Aug 7 11:25:03 2018 Incoming Data Channel: Cipher 'AES-128-CBC' initialized with 128 bit key 
Tue Aug 7 11:25:03 2018 Incoming Data Channel: Using 160 bit message hash 'SHA1' for HMAC authentication 
Tue Aug 7 11:25:03 2018 ROUTE_GATEWAY 192.168.1.1/255.255.255.0 IFACE=enp2s0 HWADDR=1c:1b:0d:09:5f:af 
Tue Aug 7 11:25:03 2018 TUN/TAP device tun0 opened 
Tue Aug 7 11:25:03 2018 TUN/TAP TX queue length set to 100 
Tue Aug 7 11:25:03 2018 do_ifconfig, tt->did_ifconfig_ipv6_setup=0 
Tue Aug 7 11:25:03 2018 /sbin/ifconfig tun0 172.31.0.6 pointopoint 172.31.0.5 mtu 1500 
Tue Aug 7 11:25:03 2018 /sbin/route add -net 192.168.1.0 netmask 255.255.255.0 gw 172.31.0.5 
SIOCADDRT: Network is unreachable 
Tue Aug 7 11:25:03 2018 ERROR: Linux route add command failed: external program exited with error status: 7 
Tue Aug 7 11:25:03 2018 /sbin/route add -net 172.31.0.0 netmask 255.255.255.0 gw 172.31.0.5 
SIOCADDRT: Network is unreachable 
Tue Aug 7 11:25:03 2018 ERROR: Linux route add command failed: external program exited with error status: 7 
Tue Aug 7 11:25:03 2018 Initialization Sequence Completed