The 25GB ET interfaces are not coming up between an EX4650 and EX4400.

The ports are not coming up starting from Junos 21.4R3-S3.4 to the latest 23.1. However, the ports are going up on 21.1R1.11 and 20.4R3-S3.4.

The EX4650 (et-0/0/0) is directly connected to EX4400 (et-0/2/0 ) using SFP28-25G-BASE-LR.

Ex4560-----et-0/0/0----------et-0/2/0-----Ex4400

The interface configuration and its looks good, no issue duplex, speed and auto-negotiation.

Verified the FEC mode on both Ex4400 and Ex4650 and identified that in Ex4400 FEC mode none is enabled by default; however, in Ex4650 FEC74 is enabled.

Changed the FEC value as none in the Ex4650 switch, post that the interface came up as expected.

User@switch# set interfaces et-0/0/0 gigether-options fec none
User@switch# show | compare
[edit interfaces et-0/0/0]
+    gigether-options {
+        fec none;
+    }

{master:0}[edit]
User@switch# commit
configuration check succeeds
commit complete

User@switch# run show interfaces terse | match et-0/0/0
et-0/0/0                up    up
et-0/0/0.0              up    up   eth-switch