Lost messages sent simultaneously


I am using MQTT gateway with ENC28J60 ethernet and around 20 nodes over rs485.
I encounter issue with covers. When all covers are triggered to close/open in the same time, some of them are not triggered. From the hardware topology - there is one node responsible for all covers. So each of cover request receive own message to that module (with own sensor id). After logs investigation I see that last messages are not delivered (around after 5th) to the node at all - this is probably the reason. I think this is the problem of rs485 nature. Is there any solution how to avoid this? Maybe just to resend the message(on software level) if no ack has been received?

Best regards,