You might need to look at networking when you get a "debug1: Connecting to hostname port 22." message.

If you manage the networks / IP ranges - perhaps there's something unusual or local you can look at with the switch / hub / router. If you don't have access to networking information or the switch - then a tcpdump to filter for that remote address / host might give one of us enough clues to help further. If you have both machines and they are close - setting up a point to point network would let you know if this is truly on the OS side of the other ssh side. (Although you've already looked at the tcpdump - so posting that can be problematic and many people won't parse them online)

I've never needed to enable logs / look at them on the macOS sshd side but perhaps that would also let you know more?

worst case you edit the post to explain a bit more:

• what OS version is ssh?
• What OS version is sshd?
• How exactly are things connected?
• Is the failure bilateral (can the problematic Mac ssh out but not allow ssh in)?

Assuming the date and time on both computers are within 10 seconds of each other, you might need to look at networking when you get a "debug1: Connecting to hostname port 22." message.

If you manage the networks / IP ranges - perhaps there's something unusual or local you can look at with the switch / hub / router. If you don't have access to networking information or the switch - then a tcpdump to filter for that remote address / host might give one of us enough clues to help further. If you have both machines and they are close - setting up a point to point network would let you know if this is truly on the OS side of the other ssh side. (Although you've already looked at the tcpdump - so posting that can be problematic and many people won't parse them online)

I've never needed to enable logs / look at them on the macOS sshd side but perhaps that would also let you know more?

worst case you edit the post to explain a bit more:

• what OS version is ssh?
• What OS version is sshd?
• How exactly are things connected?
• Is the failure bilateral (can the problematic Mac ssh out but not allow ssh in)?

You might need to look at networking when you get a "debug1: Connecting to hostname port 22." message.

If you manage the networks / IP ranges - perhaps there's something unusual or local you can look at with the switch / hub / router. If you don't have access to networking information or the switch - then a tcpdump to filter for that remote address / host might give one of us enough clues to help further. If you have both machines and they are close - setting up a point to point network would let you know if this is truly on the OS side of the other ssh side. (Although you've already looked at the tcpdump - so posting that can be problematic and many people won't parse them online)

I've never needed to enable logs / look at them on the macOS sshd side but perhaps that would also let you know more?

worst case you edit the post to explain a bit more:

• what OS version is ssh?
• What OS version is sshd?
• How exactly are things connected?
• Is the failure bilateral (can the problematic Mac ssh out but not allow ssh in)?

You might need to look at networking when you get a "debug1: Connecting to hostname port 22." message.

If you manage the networks / IP ranges - perhaps there's something unusual or local you can look at with the switch / hub / router. If you don't have access to networking information or the switch - then a tcpdump to filter for that remote address / host might give one of us enough clues to help further. If you have both machines and they are close - setting up a point to point network would let you know if this is truly on the OS side of the other ssh side. (Although you've already looked at the tcpdump - so posting that can be problematic and many people won't parse them online)

I've never needed to enable logs / look at them on the macOS sshd side but perhaps that would also let you know more?

worst case you edit the post to explain a bit more:

• what OS version is ssh?
• What OS version is sshd?
• How exactly are things connected?
• Is the failure bilateral (can the problematic Mac ssh out but not allow ssh in)?