After getting April 2018 security patch, I tried to update it through OTA as usual process. However, after updating, my Nokia 8 stoped detecting simbin slot 2 (tried various network operators). Then I had to go to service centre to downgrade my software to Jan 2018 patch. And surprisingly it started working. Later, again after updating to April 2018 security, sim slot 2 stopped working. This happened 4 times and now service centre guy gave me a solution to NOT TO UPDATE your phone. Very much disappointed.