Issues with 2.5g realtek and XS1930-10

malakudi
malakudi Posts: 39  Freshman Member
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in Switch
I got myself a Zyxel XS1930-10 switch and I am using it with a PC with MSI X570 Unify motherboard that has a RTL8125 2.5 Gbps LAN controller. XS1930-10 is then connected to my XGS1930-28HP with a 10g SFP+ patch cord.

My ethernet infrustructure is all cat6 certified (running cables, patch cords, patch panel and terminals). I have problem autonegotiating 2.5g speed. Most of the time it negotiates at 1g. Sometimes it negociates 2.5g . If I force the port at 2.5g, PC can take up to 4-5 minutes to connect at 2.5g. After it connects, everything works fine, there are no disconnects.
I also have NWA210AX which always connects to 2.5g at the same terminal/cable that my PC also is using, so it is definitely not the cabling.

Since I want to upgrade other equipment to 2.5g or more, I want to know if there is a known issue with Realtek RTL8125 and if not, what might be the problem for my case?

Thank you 

All Replies

  • Zyxel_Chris
    Zyxel_Chris Posts: 705  Zyxel Employee
    Zyxel Certified Network Administrator - WLAN Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate 50 Answers
    @malakudi,
    Can you please auto-negotiate the link on the 2.5G connection and then collect the tech-support (in management> maintenance) file when the symptom occurs then send it to me via private message?

    Additionally, could you please provide the vendor name of the cat6 cable also may I know if you can put the cable from NWA210AX to XS1930 for cross-checking purposes?
  • malakudi
    malakudi Posts: 39  Freshman Member
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    I can't find management->maintenance option in Nebula, where exactly is it?

    As I already said, I tried the NWA210AX at the same RJ45 socket where I connect my PC, and NWA210AX has no problem auto-negiotiating 2.5g
    Cable is JetLan6+ UTP PVC 350MHz.
    Patch panel is Digitus with DN-93603 CAT6 Keystone
    Wall socket is Schneider MTN465706 CAT6A
    And patch cords are KPP UTP CAT6 PVC 24AWG 4PR


  • malakudi
    malakudi Posts: 39  Freshman Member
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    Also, as far as I know 2.5g should be capable with cat5e as well, no need for cat6.

    I am pretty sure the problem is on the motherboard's RTL8125 adapter. But I need to know if this is a specific problematic adapter or there is an incompatibility with all RTL8125 devices.

    I will try to get another computer with RTL8125 to test. I also ordered a USB3 to 2.5g ethertnet with a different Realtek chipset, to test as well.

    I would buy Intel X550 but it is quite expensive, more than 300 euro where I live.

  • mMontana
    mMontana Posts: 1,389  Guru Member
    50 Answers 1000 Comments Friend Collector Fifth Anniversary
    Tried with a Linux live to see if there are the same issues about autonegotiation?
  • malakudi
    malakudi Posts: 39  Freshman Member
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    Yes, same issue with Linux. When the port speed in switch is configured as "Auto", driver mentions downshift and to check cables. But as I already said, on same cables/wall socket/patch cord, NWA210AX always does 2.5g autonegotiation.
    When the port speed in switch is at fixed 2.5g, then PC tries to connect around 4-5 minutes, until it finally does 2.5 connection. After that, it works just fine, no disconnects or other problems. I even tested speeds with iperf3 from 3 different 1g devices, and got near 2.5g performance (around 820mbps per destination).
    It seems that either the NBASE-T autonegotiation is somehow incompatible/broken between this RTL8125 and the switch, or that the specific adapter on the specific motherboard is problematic.
  • malakudi
    malakudi Posts: 39  Freshman Member
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    I just noticed that on the switch port where the PC connects, I have some RX CRC errors.
    Info says "CRC errors indicate packet error in the network, potentially caused by bad cables or transceivers. Please check your physical connection to resolve it".
    Since cabling works fine for NWA210AX, I would assume the issue lies on the transceiver of RTL8125?

    If pins inside the RJ45 socket on the motherboard have bent or got corrosion, would experience such behavior?

    What puzzles me is that after "training" manages to get 2.5g, then everything works fine. If there was a permanent issue, it would give disconnections all the time.


  • mMontana
    mMontana Posts: 1,389  Guru Member
    50 Answers 1000 Comments Friend Collector Fifth Anniversary
    I can only suggest you to do some research on this chip and the implementation on your motherboard.
    For the "fast" negotiation among AP and switch, i'd mark it as a "nice case" but it's only 1 good vs 1 bad on your setup.
    2.5G and 5G standards should work (as goal) also with CAT 5e, however products are on the market for few years, so i currently don't know which is compatibility among devices and the experience on these kind of devices.

  • Zyxel_Chris
    Zyxel_Chris Posts: 705  Zyxel Employee
    Zyxel Certified Network Administrator - WLAN Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate 50 Answers
    @malakudi,
    Since your device is on Nebula and there is the CRC warning, I can help to check if there is further information, please activate the "invite Zyxel support" in Help> Center and private message me your org./site name and the timestamp.
  • malakudi
    malakudi Posts: 39  Freshman Member
    First Comment Friend Collector First Anniversary
    Got a USB 2.5g ethernet adapter with RTL8156B chipset. This does 2.5g auto-negotiation immediately.
    So it is either a problematic RTL8125B chip on my motherboard or a compatibility issue between XS1930 and RTL8125B. 
    Will have a new motherboard with RTL8125B soon to test that as well.

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