Error E03-H3-10

[Sux]

Both me and my fianceé have the game on Steam, when I try to invite him to my party it works normally, he gets an invite, but after accepting it says party does no longer exist, and this text shows up on the error window. E03-H3-10
After me reinstalling the game it just says "Leaving session" on his screen, takes pretty long, and eventually the text goes away and nothing happens.

[Team17_Assist]

Hey Sux,

We're sorry to hear you're having this issue with playing online.

• Are you both playing on the same internet connection or different connections from different locations?

So we can ensure you have the best connection, can you please BOTHfollow the steps in this article[team17.helpshift.com], and reach out to your Internet Service Provider (ISP) to open your NAT?

If you are still experiencing connection issues after performing the steps in the article provided above and opening your NAT, can you please tell us the following information:

1. What country are you currently living in?
   
2. Steam Download Region (Steam Settings, Downloads)
   
3. What is your internet speed? Internet Speed Test[www.speedtest.net]
   
4. Are you using a VPN?
   
5. What is your NAT set to?

We look forward to hearing back from you.

Regards,
Team17 Support