diff --git a/src/sw_sup/drtio.md b/src/sw_sup/drtio.md
index 7dbdaaa..7ad95eb 100644
--- a/src/sw_sup/drtio.md
+++ b/src/sw_sup/drtio.md
@@ -58,6 +58,7 @@ artiq.coredevice.exceptions.RTIODestinationUnreachable: RTIO destination unreach
 * Mismatch with real SFP port and the one, specified during device_db generation: re-attach the SFP ports according to
   device_db or regenerate device_db according to SFP port attachment.
   [More info at the device_db article.](device_db.md)
+* The SFP slots used are designated for [CoaXPress-SFP](../hw/coaxpress_sfp.md), please use other SFP slots.
 
 ### Master-satellite interrupted/unstable connection