Between Router and Switch uplink port sync in half duplex speed 10

[naeemu518]

i have router the model of 2811 and also switch which is power over ethernet (POE). two ports of router which is fast ethernet port and switch have 24 ports fast Ethernet and 4 Gigabit Ethernet port SFP. the issue is that i have use the port of router is fastethernet0/0 and switch port is use fastethernet0/24, all the parameters are same between point-to-point connection like MTU, Speed, duplex but still the port sync in half-duplex manually set full duplex and speed the port is down and remove the manually configuration then the port is up in half duplex. 

[M02@rt37]

Hello @naeemu518 

The fact that ports going down, is typically due to mismatched auto-negotiation settings or hardware limitations. First, ensure that both the router and switch have consistent auto-negotiation settings—either enabled on both or disabled on both. Verify interface settings using show running-config interface x/x and check the interface status with show interfaces to identify any errors or duplex mismatches.

Disable auto-negotiation on both devices and manually set the speed and duplex settings using commands like no negotiation auto, speed 100, and duplex full. 

Do you ensure that the ethernet cable is in good condition and properly rated ? ... try different ports if necessary.

Take a look to device logs for any messages indicating why the ports are reverting to half-duplex: show logging.

[naeemu518]

the port is changed of router and switch and also change the ethernet cable but still same issue. only one thing is remaining auto-negotiation command at both end. thank you for response i will try to apply this command.