Hey Herastean, that error code is a generic disconnection code and doesn't give us enough information however we do think it might have to do with a firewall issue, I'm going to link the support for that particular code which has several different directions for (trying) fixing it.
[url="https://us.battle.net/support/en/article/624?utm_campaign=BlizzardCSEU&utm_medium=posting&utm_source=internal-support_forums&utm_content=120716"><s>https://us.battle.net/support/en/articl ... ent=120716">https://us.battle.net/support/en/article/624?utm_campaign=BlizzardCSEU&utm_medium=posting&utm_source=internal-support_forums&utm_content=120716[/url]
[url="https://us.battle.net/support/en/article/624?utm_campaign=BlizzardCSEU&utm_medium=posting&utm_source=internal-support_forums&utm_content=120716"><s>https://us.battle.net/support/en/articl ... ent=120716">https://us.battle.net/support/en/article/624?utm_campaign=BlizzardCSEU&utm_medium=posting&utm_source=internal-support_forums&utm_content=120716[/url]