Etherchannel will not form due to many mismatches like channel group ID, operational mode, and allowed vlans.
1. Channel group ID mismatch: The channel group ID specified on S1 is 1, while the channel group ID specified on S2 is also 1. Therefore, there is no mismatch in the channel group ID.
2. Operational mode mismatch: The operational mode is set to "active" on both S1 and S2. Therefore, there is no operational mode mismatch.
3. Allowed VLANs mismatch: On S1, the allowed VLANs are configured as 1-5, while on S2, the allowed VLANs are configured as 1, 5, and 10. Since the allowed VLANs do not match exactly, there is a mismatch in the allowed VLANs.
Based on the provided information, the mismatch in the allowed VLANs prevents Etherchannel from forming.