Tankless water heater dims lights, interrupts the internet and caused static on the radio

I recently replaced my Rheem RTE13kw tankless water heater with the newer version of the same heater(RTEX13KW). The new water heater causes a group of wall lights that are all on the same switch to dim…no other lights in the house are affected. While the water heater is running the internet will not work at all, and the radio will have a lot of static. The old water heater never had these issues. The lights dim the worst when the water is on low and when only the #1 heating element is on. With the water on high the lights seem fine, but the internet still doesn't work. I have run all the diagnostics on the heater that Rheem provides in the troubleshooting guide and I have found no issues with the water heater. If there is anybody that can give me some ideas it would be very helpful.