Windows 10 User automatically gets banned

Hey,
my friend hosts a mce server using pmmp, and when i try to connect on it via windows minecraft version it says "Blocked *IP* for 5 seconds" in his console.

Does it have to do with PHP?

• PocketMine-MP:1.7dev-708m / using version 3.0.0-alpha11 api for mce v1.2.10 (protocoll version 201)
• PHP: 7.2
• Server OS: android / 1.2.10
• Game version: server hosted on android

 

Some more context:
https://github.com/pmmp/PocketMine-MP/issues/2013