Running Valheim Dedicated Server on Ubuntu 20.04 (server) on aarch64, Raspberry Pi 4 (8GB)
Box64 with Dynarec v0.1.3 39f2b50 built on Aug 26 2021 10:33:55
Using Valheim Dedicated Server for Linux downloaded via steamcmd

Good news is, I got it to work, played successfully over one hour with two players on the server.

However, the server ist not stable. After several hours idle, I cannot re-connect and have to restart the server. Restart fails in about 7 of 10 attempts with the following "Unimplemented Opcode Message":

Aug 26 10:39:00 raspi4 vstart.sh[13078]: (Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39)
Aug 26 10:39:00 raspi4 vstart.sh[13078]: 08/26/2021 10:39:00: Game server connected
Aug 26 10:39:00 raspi4 vstart.sh[13078]:
Aug 26 10:39:00 raspi4 vstart.sh[13078]: (Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39)
Aug 26 10:39:01 raspi4 vstart.sh[13078]: TYPE: 31
Aug 26 10:39:01 raspi4 vstart.sh[13078]: * Assertion at mini-amd64.c:209, condition `amd64_is_imm32 (disp)' not met
Aug 26 10:39:01 raspi4 vstart.sh[13078]: Warning, jumping to a no-block address 0x6490a5c0 from 0xffff78032770 (db=0xa0c7ca70, x64addr=0xffff8cfa9b7c)
Aug 26 10:39:01 raspi4 vstart.sh[13078]: 13078|0x6490a5ae: Unimplemented Opcode (D9) FE 97 60 02 40 F9 77 D9 FE 97 05 FF FF 17 1F
Aug 26 10:39:02 raspi4 vstart.sh[13077]: /home/valheim/Valheim/vstart.sh: line 12: 13078 Aborted (core dumped)

I'll attach the complete server log. Hope you can help me with this, thanks in advance.
Server Log Valheim Dedicated Server on Raspi4.txt