XS1930-10: Setup Wizard Lock-Up, DAC Instability, Internet Bandwidth Drop, and LACP Port Errors

Giuliano · November 10

Hello everybody.

I have seen that there is a lot of literature on XS1930-10 already, so I tried to navigate a bit but I'm not sure I can get to a solution that way - as it is my impression that I have different issues that may though be linked together.

I'm not an IT professional, so I apologise in advance is anything is not clear.
Below I summarize my issues and the steps already taken:

Subject: XS1930-10: Setup Wizard Lock-Up, DAC Instability, Internet Bandwidth Drop, and LACP Port Errors

📡 Network Topology Overview:

[RT-AX89X Router]
│ DAC 10G (0,5m, 10GTek)
▼
[XS1930-10 Switch] (port 9)
├─ Port 10 → DAC 10G (2m, 10GTek) → [XGS1250-12 Switch]
│ └─ Port 9 → Main PC Desktop (2.5G)
├─ Port 1 → [NAS Asustor AS6706T LACP] (2.5G)
├─ Port 2 → [NAS Asustor AS6706T LACP] (2.5G)
├─ Port 3 → [NAS Asustor AS3304Tv2] (2.5G)
├─ Port 4 →
├─ Port 5 →
├─ Port 6 →
├─ Port 7 → [RT-AX86U Mesh Node] (2.5G backhaul LAN)
├─ Port 8 → [Zyxel GS1200-5 Switch] (1G)
├─ TV
├─ AV Receiver
├─ Blu-ray Player
└─ Nvidia Shield TV Pro

All cables are either certified DAC or Cat 8.1.

For ports 9 and 10, DDMI info:

Transceiver Information

Port No	9
Connector Type	SFP
Vendor	OEM
Part Number	SFP-H10GB-CU1M
Serial Number	CSC250605930048
Revision	R
Date Code	2025-06-09
Transceiver	Others

Transceiver Information

Port No	10
Connector Type	SFP
Vendor	OEM
Part Number	SFP-H10GB-CU3M
Serial Number	CSC210601660468
Revision	R
Date Code	2021-06-10
Transceiver	Others

All baseT cables are from 1attack.de

Technical details:

Connections:

Connection, shielding: yes.
Connector 1, Type: RJ45 Male (8P8C)
Latch protection: on both sides.
Connector 2, Type: RJ45 Male (8P8C)

Cable.

Shielding class: S/FTP (PiMF).
Specification: CAT 8 according to IEC 46C/976/NP.
Inner conductor, material: CU (copper).
AWG 24 (flexible copper cores).
Number of shields: 2 x
- Type 1, shielding: foil (aluminium) PiMF.
- Type 2, shielding: braid (aluminium) overall shade.
Diameter: cable sheath 8.2 mm.
Kink protection: on both sides.
LSZH compliant: yes.
Cable type: round cable.

Signal transmission.

Max. Bandwidth: 2000 MHz, 25GBase-T / 40GBase-T.

General

Outer sheath material: LSZH halogen free.
Poe+ suitable.

🧪 Verified Configuration:

All ports correctly negotiate their intended speeds (2.5G or 10G).
Jumbo Frames (MTU 9000) are enabled across NAS, router and PC.
QoS is disabled on router (picture at the point 2 below)
Loop Guard is active on the XS1930-10.
Firmware is up to date

System Name	System Location
XS1930	Server - MAIN
Boot Version	ZyNOS F/W Version
V1.00 \| 08/26/2019	V4.80(ABQE.4) \| 08/23/2024
	Hardware Version
	V1.3

Errors

Port 1 (the communication between PC and NAS only flows through this port)

Error Packet

RX CRC	0
Length	1
Runt	0

Distribution

64	21534285
65 to 127	4688423
128 to 255	726399
256 to 511	970215
512 to 1023	250068
1024 to 1518	128730377
Giant	2386485

Port 3 (second NAS)

Error Packet

RX CRC	0
Length	4
Runt	0

Distribution

64	1344575
65 to 127	10557975
128 to 255	140944
256 to 511	95332
512 to 1023	66572
1024 to 1518	4023058
Giant	61474985

⚠️ Issues Observed:

1. Setup Wizard Lock-Up

Static IP could not be configured unless set via Zyxel ZON Utility.
Running the setup wizard (before or after firmware update) causes the switch to freeze and become unresponsive.
Requires manual reboot / factory reset to recover (in both case losing config)
This behaviour is consistent and reproducible.

2. DAC Instability Between Switches

Initial DAC link between XS1930-10 and XGS1250-12 was unstable and kept on reverting to SFP+
After manually configuring the DAC on XGS1250-12 and updating firmware, stability improved.

XGS1250-12

XS1930-10

3. Internet Bandwidth Drop

Internet bandwidth (which passes through the XS1930-10) dropped significantly after switch installation.
Previously: ~2000+ Mbps download from PC.
Now: ~1350 Mbps download from PC
In a few cases, when high bandwidth tasks were launched (network speed test, internet speed test, game download from Steam, …) the XS1930-10 would freeze until rebooted manually
Drop is consistent with the performance degradation observed in NAS transfers.

From PC APP

From Router APP

4. NAS Performance Regression

NAS AS6706T Gen 2 previously connected via XOR to XGS1250-12 → Zyxel MG-108 (unmanaged) → PC.
In that setup, NAS APP and iperf3 tests showed symmetrical and expected 2.5G performance (~2450 Mbps up/down).
After migrating to XS1930-10 with LACP, performance dropped and became asymmetric. (~1350 Mbps NAS—>PC / ~2450 PC—>NAS)
iperf3 single-stream saturates one link (~2.3 Gbps), but multi-stream tests show imbalance.
NAS recently reported “LAN 2 lost” despite both LACP ports showing active on the switch.
No disconnection logs except during LACP mode changes (for testing).
Similar situation for the NAS AS3304T - with now ~620 Mbps NAS—>PC / ~2450 PC—>NAS

5. Previous Topology (no speed issues)

I would like to clarify that the only new variable are:

XS1930-10
0.5m DAC cable Router —> XS1930-10

[RT-AX89X Router]
│ DAC 10G (2m, 10GTek)
▼
[XGS1250-12 Switch] │
├─ Port 9 → [NAS Asustor AS6706T LAG XOR] (2.5G)
├─ Port 10 → [NAS Asustor AS6706T LAG XOR] (2.5G)
├─ Port 11 → [Zyxel MG108] (2.5G)
└─ Port 12 → [RT-AX89X] (10G)
[Zyxel MG108] (2.5G)
├─ Main PC Desktop (2.5G)
├─ [RT-AX86U Mesh Node] (2.5G backhaul LAN)
├─ [NAS Asustor AS3304T]
├─ [Zyxel GS1200-5 Switch] (1G)
├─ TV
├─ AV Receiver
├─ Blu-ray Player
└─ Nvidia Shield TV Pro
└─ Other wall ports

🔍 Request for Support:

Clarify known issues with the setup wizard and "bandwidth demanding jobs" causing system lock-up.
DAC link instability and configuration loss during initial setup.
Diagnose cause of bandwidth drop affecting both NAS and internet throughput.
Help with possible reasons for “LAN 2 lost” under LACP, despite active ports.
Recommend best practices for stable LACP and DAC operation on XS1930-10.
Any other recommendation

Thanks a lot for your patience, I know it is a lot to read but it's two weeks of fights summarised as best as I can 😅😃

Zyxel_Tina · November 10

Hi @Giuliano,

Thank you for your detailed feedback regarding the issues with your XS1930-10 switch.

To better assist you, please clarify the following questions and provide the Tech-support Info file:

Could you please describe more about the Setup Wizard Lock-up? For example, how did you configure it, and what were the original and new IP addresses you attempted to set via the wizard?
When you observed the Speedtest bandwidth drop, were there other clients using bandwidth on the network at the same time?
Please provide the XS1930’s Tech-support Info file via private message so we can investigate further.
1. [Switch] How to collect the Tech-support Info on V4.80 firmware version and newer? — Zyxel Community

Giuliano · November 10

Hi Tina,
Thank you in the first place for coming back to me.

Wizard

I simply cannot use it - whatever operation I run on it, the switch freezes as soon as I apply any change and once rebooted it reverts to its basic setup
Static IP setup - I was only able to finalise this through ZON - whenever I tried earlier on from GUI (apart from the Wizard) the system would fail retaining the static IP

Speed tests

All my speed test were done in "optimal conditions", to avoid noise.

HOWEVER - during the weekend I played a bit more with the configuration, and I:

toggled Jumbo Frames OFF on all devices
toggled the Port Buffer ON for ports 1-3
- ports 1-2 —> LACP 1-2 NAS AS6706T
- Port 3 —> Single port NAS AS3304T
- Set by default and unchangeable for ports 9-10 (Router —> XS1930-10 —> XGS1250-12)
toggled the Flow Control ON on ports 4-10 - as it is not possible for trunk ports

Results

Deactivating the Jumbo Frames regained 200 to 300 mbps
Activating the Port Buffer and the Flow Control resumed the full, symmetric speed for the LAN (confirmed as well with iperf3) ~2450/2450

—> I still had some freezing happening when testing the WAN Speed - the router would remain active with no apparent issue, except that it wasn't reachable via LAN and there was no bandwidth going through.
The router was accessible via DDNS service though.

I've rebooted but only tested again the WAN speed this evening and so far I had 2000+ mbps DL / 950+ mbps UL without freezes.

It is possible that these changes in the configuration sorted thispart out (is it?).

I nonetheless downloaded the Info File you requested and I will share it with you as directed, for your perusal.

Have a nice evening

Giuliano

Zyxel_Tina · November 12

Hi @Giuliano,

Thank you for providing the detailed information and the tech-support file regarding your experience with the XS1930-10 switch.

Here is a breakdown and some guidance: