As you have no logs available, I suppose that you cannot replicate the case easily.
But if you confirm that the failed Remote Adapter must stay alive and does not disconnect, then I'm afraid there is nothing available to recover.
In fact, you cannot communicate with a Proxy Adapter to force it to discard the current connection;
moreover, the Proxy Adapter does not perform any check on the keepalive messages received (they were only added to the benefit of the O.S. or any intermediaries).

Only in case of a Remote Data Adapter, should it be aware of running into problems, it could try to invoke the Failure method on the IItemEventListener;
the "robust" Proxy Adapter would let just that connection fail and would recover the issue.

Anyway, at the moment, the only way to force a Remote Adapter to disconnect is to operate on the socket in some way, perhaps by putting something in the middle.