Besides the KRACK vulnerability was fixed by an update on 24th October, prior even to the 17.10.2 update.
As to your problem.
I am unfortunately lost, as the update worked absolutely smooth for me.
I guess nothing else has changed besides the update; as you surely would have checked that (new app installed, new router …).
Are you on the Fairphone OS or OOS?
Just hope, some technically able person can help you.