Maplotter

I am feeling despondent and desperate, and I kindly seek your advice and guidance. I have three 5kW Synerji inverters configured to operate in parallel. Each inverter has its own 4260W solar array. One of the inverters threw error code 09, so I sent it away for repairs. After receiving it back, the inverter started cutting out as soon as the solar input reached around 3000W, then restarted and began supplying power again—only to repeat the cycle. Occasionally, it trips at even lower current levels. I returned it again, and it appears the repair center replaced the MPPT unit. However, now my other two inverters are throwing error code 71 with a flash "NE" and they no longer communicate with each other. All three originally had U1 firmware version 74.40 and U2 version 04.12. The one with the replaced MPPT now shows U1 firmware version 12.21, while U2 remains at 04.12. I would greatly appreciate it if you could help point me in the right direction regarding why the inverter initially started clipping, and why the U1 firmware is now 12.21 after, according to them, only the MPPT was replaced.