Inbound messages stopped

Outbound email is OK.

Inbound email goes through GWIA, but fails to reach recipients mailboxes.

In the POA log, it says:

22:43:27 2A5 Message Transfer Protocol:
22:43:27 2A5 Inbound MF traffic: 192.168.0.82, 7100
22:43:27 2A5 Outbound MF traffic: 192.168.0.82, 7100
22:43:27 2A5 Message Transfer over SSL: Disabled
22:43:27 2A5 MTP File Transfer Size Limit: 0 MB (No Limit)

then a few seconds later:

22:43:38 2FA MTP: Waiting for busy LISTEN socket to become available
22:43:48 2FA MTP: Waiting for busy LISTEN socket to become available
22:43:59 2FA MTP: Waiting for busy LISTEN socket to become available
22:44:09 2FA MTP: Cannot initialize for LISTEN [B309]. All inbound
traffic will be blocked.
22:44:09 2FA MTP: Port 7100 is already in use, terminating MTP listener

So I assume this is the reason.

The MTA is set to use port 7100, and the link configuration is set to
use port 7100. Should these be different?

TIA
p