[strongSwan] Interface can't be the loopback interface (lo). Sorry. - problem

[lejeczek]

hi guys

I found this: https://wiki.strongswan.org/issues/294

Both ends of my tunnel are Fedora29, so version of Strongswan should be 
that-bug-free, it's: Linux strongSwan U5.7.1/K4.19.10-300.fc29.x86_64

But still when up my tunnel, it's successful with that one problem:

....

scheduling reauthentication in 3228s
maximum IKE_SA lifetime 3528s
installing DNS server 10.3.1.99 via resolvconf
resolvconf: Interface can't be the loopback interface (lo). Sorry.
removing DNS server 10.3.1.99 via resolvconf
resolvconf: Interface can't be the loopback interface (lo). Sorry.
adding DNS server failed
installing DNS server 10.3.1.99 via resolvconf
resolvconf: Interface can't be the loopback interface (lo). Sorry.
removing DNS server 10.3.1.99 via resolvconf
resolvconf: Interface can't be the loopback interface (lo). Sorry.
adding DNS server failed
handling INTERNAL_IP4_DNS attribute failed
installing DNS server 10.3.1.99 via resolvconf
resolvconf: Interface can't be the loopback interface (lo). Sorry.
removing DNS server 10.3.1.99 via resolvconf
resolvconf: Interface can't be the loopback interface (lo). Sorry.
adding DNS server failed
handling INTERNAL_IP4_DNS attribute failed
installing new virtual IP 10.3.1.18
selected proposal: ESP:AES_CBC_128/HMAC_SHA2_256_128/NO_EXT_SEQ
CHILD_SA jatymy{99} established with SPIs 9d2f935b_i 8e9ee36d_o and TS 
10.3.1.18/32 === 10.3.1.0/24
connection 'mytunnel' established successfully


How can troubleshoot it and more importantly how to fix it?

many thanks, L.