Thank you Colaxais & AcceptWorldcoins for your responses.
Using the old wallet could  possibly resolve my problem.

I got the network alert when launched v0.8.6.1-30-g7ca106d-beta version from your link.
Is it safe to use that version? No hardfork occurred since or is going to?

edit: I compiled also v0.8.6.2-g55c5572-beta and got the same alert.