# Why Does a 100 Mbps Port Report a 10 Mbps Link?

**URL:** <https://forum.botblox.org/t/why-does-a-100-mbps-port-report-a-10-mbps-link/636>\
**Category:** BotBlox Hardware\
**Tags:** switchblox-ind\
**Created:** [August 21, 2026, 4:08pm UTC](https://forum.botblox.org/t/why-does-a-100-mbps-port-report-a-10-mbps-link/636 "2026-08-21T16:08:43Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ElsieMichaelson](https://avatars.discourse-cdn.com/v4/letter/e/b5ac83/32.png) [@ElsieMichaelson](https://forum.botblox.org/u/ElsieMichaelson)\
**Post date:** [August 21, 2026, 4:08pm UTC](https://forum.botblox.org/t/why-does-a-100-mbps-port-report-a-10-mbps-link/636/1 "2026-08-21T16:08:43Z")

</div>

_This topic was migrated from the BotBlox ticketing system after being summarized and anonymized._

**Question:**

I have configured a port on the botblox industrial to be:

1. no autonegotiation
2. 100 Mbps / full duplex

I also configured the ports to only advertise the 0x04 (100/full) config and saved the configuration to ensure that those persist on power cycle. Then I powered-on our system and ran the port # phy show command to confirm the speed/duplex that each port was setup as and noticed the following. Is it possible for a link to report 10/full if the advertised modes do not include 10/full?

**Answer:**

Yes, I believe this can happen on the SwitchBlox Industrial.

When auto-negotiation is disabled, the advertised-mode setting is effectively no longer involved in determining the link speed — the PHY is operating from the forced speed/duplex configuration instead.

There is also a power-saving feature in the IP175G PHY called WOL+ down-speed. This can temporarily reduce a 100 Mbps link to 10 Mbps when the port is idle, and the feature is enabled by default.

That would explain why `phy show` can report 10/full even though 10/full is not included in the advertised modes.

So in this case I don’t think the PHY has actually negotiated an unadvertised 10/full mode; I suspect you’re seeing the WOL+ down-speed behaviour.

If you need the port to remain strictly at 100/full at all times, we should disable the WOL+ down-speed function as well.