Brown Out when generator connected

[Hazex4]

I have a 2021 Montana 3120RL. When I connect to shore power whether 50 or 30 amp service my voltage reading is normal at 115-120. When I connect 15 amp house power I get good voltage readings. When we're dry camping the 3000W inverter shows good readings. I have 2 Honda 2000 generators, if I connect either of them individually I get 65volts and a Brown Out warning. I get the same bad reading if I connect them in parallel, this configuration gets me to 30amps. I borrowed my neighbors 4000W/30amp generator and got the same bad readings with Brown Out. There were no loads on any of the generators when connected. I took my Honda generators to the dealership and they both check 4.0. Anyone else have this problem?