I need help using a server.jar file.

It doesnt work while trying to install a datapack (Oneblock skyblock) and it just makes a bunch of error/crash reports. Server.jar file is 1.16.4.

Heres the crash report I got a few minutes ago. (all of them are the same)

Time: 11.2.2021 20:56
Description: Exception in server tick loop

java.net.UnknownHostException: oneskyblock.net
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(Unknown Source)
at java.net.InetAddress.getAddressesFromNameService(Unknown Source)
at java.net.InetAddress.getAllByName0(Unknown Source)
at java.net.InetAddress.getAllByName(Unknown Source)
at java.net.InetAddress.getAllByName(Unknown Source)
at java.net.InetAddress.getByName(Unknown Source)
at zg.d(SourceFile:137)
at net.minecraft.server.MinecraftServer.w(SourceFile:645)
at net.minecraft.server.MinecraftServer.a(SourceFile:257)
at java.lang.Thread.run(Unknown Source)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
Minecraft Version: 1.16.4
Minecraft Version ID: 1.16.4
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_261, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1049087200 bytes (1000 MB) / 1580728320 bytes (1507 MB) up to 3804758016 bytes (3628 MB)
CPUs: 8
JVM Flags: 0 total;
Data Packs: vanilla, file/ija-one-block (incompatible)
Is Modded: Unknown (can't tell)
Type: Dedicated Server (map_server.txt)