I've tried to install Appwrite on custom port (ex. 8888). Once installation completed, I can signup new server but cannot login to console.
I've went to Appwrite's support discord channel and got the answer. The problem is because Appwrite not able to save cookie since the combination of IP address and custom port. So I map my subdomain to the server and now I can access Appwrite console.

I think this might be the line causing this issue, will take a deeper dive a bit later:
https://github.com/appwrite/appwrite/blob/e6c06040ff1402266d771e75d3466af8f6cb3c67/app/init.php#L78
Fixed. Patch will be released with 0.6.2...
Version 0.6.2 is out 🚀🎉
Full change log: 
https://github.com/appwrite/appwrite/releases/tag/0.6.2