Depending on the relays used, there are currently connectivity issues for some users in filtered or restricted networks. VPNs are often another way of restoring connectivity; by allowing diverse ways to connect via self-hosted chatmail relays or classic mail servers, Delta Chat gives you other options to handle these connectivity issues even without a VPN.
It would help our team (and others) a lot if you could send us logs of failed or successful connection attempts, with or without VPN.
You can extract these logs in the “Advanced > View Logs” settings. Please send them to us via Delta Chat, or alternatively via E-Mail to delta@merlinux.eu. Do not publish these logs on the Internet, as they may contain identifying data.