Slow uplink on MS130-24X on 2.5G ports only

[LOTRouter]

I ran into a strange issue yesterday when using an MS130-24X plugged into a Spectrum Internet router.  If I plugged my PC directly into the Spectrum router, I got full speed (930/35).  If I plugged my PC into the MS130-24X which was also plugged into the same Spectrum router, I got really bad upload speeds (350/0.7).  After troubleshooting for awhile, I finally moved the connection from the Spectrum router to a NON-2.5G port, and I suddenly got full speed with my PC connected to the MS130.  I checked, and it properly negotiated 1G full duplex when connected to a 2.5G port, but had completely borked upload speeds.  Is this a known issue with the MS series switches 2.5G ports?

I first noticed this issue due to bad upload speeds when wirelessly connected to an MR57 connected to the same MS130, so it most certainly was not an issue with my PC's NIC.  Moving the Spectrum link to a 1G only port resolved the Wi-Fi issue as well.

[PhilipDAth]

Interesting.  What speed did the 2.5G report it was running as?  Gigabit?

[LOTRouter]

Yes, it reported as full-duplex Gigabit.  I assume I wasn't getting full download speeds due to dropped ACK packets on upload.

[cmr]

We have an MR44 plugged into one of the 2.5Gb ports of an MS130-12X and it keeps going into repeater mode.  New Cat6a cabling and not overly long...it had no issues with the MS220-8P that was there before...  I'll see if I can go there and do some direct testing as it may be related!

[LOTRouter]

Be forewarned that while ports 17-18 are not labeled as 2.5G on the MS130-24X, they will connect at 2.5G speeds.  I'm not sure if the MS130-12X has extra unlabled 2.5G ports, but I'd be sure to go with lower numbered ports, just to be sure.

[GIdenJoe]

Interesting.  Do you see any CRC errors in the live packet counters?
Is the router also negotiating correctly with that port or do you see a different negotiated speed on the router?
Remember if negotiation fails you could get stuck in a 100 Mbps half duplex setting causing plenty of collisions.

[LOTRouter]

No CRC errors, negotiated to 1G-Full, and I get greater than 100M downlink, just .07 uplink when connected to a 2.5G port.  If I move the exact same cable to an identically configured 1G only port on the MS130 then I get full speed both directions.