A count of receive overrun errors detected on this async port, meaning incoming characters arrived faster than the port's hardware/software could read them and some were lost. Note: the source MIB's DESCRIPTION text for this object ("Async port is reset after inactivity period") is clearly copy-pasted from the unrelated inactivity-timeout object and does not describe this counter; the explanation here is based on the object's own name and its position alongside the adjacent Parity/Framing error counters instead.