I tried the following today.
Using the same breadboard and only swapping out the arduino for a pin for pin match. No other jumpers or radios were changed. Summary. The Nano v3 to Nano v3 had no issues. Nano v3 RX to IoT shows gibberish received. TX from IoT shows perfect data received, but Acknowledge failed most times even though data was received.
All devices are powered from a separate 3.3V power supply with common ground to both Arduinos under test.
Test 1: Nano v3 RX to Nano v3 TX - message sent and received with the alphabet and numeric array. No TX or RX failures
Test 2: Nano v3 TX to Nano v3 RX - message sent and received with the alphabet and numeric array. No TX or RX failures
Test 3: Swapped one Nano v3 for a Nano IoT 33. Set IoT to RX.
Nano v3 serial window for TX
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Acknowledge received
Data Sent 012345678901234567890123456789 Acknowledge received
Data Sent abcdefghijklmnopqrstuvwxyz Acknowledge received
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Acknowledge received
Data Sent 012345678901234567890123456789 Acknowledge received
Data Sent abcdefghijklmnopqrstuvwxyz Acknowledge received
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Acknowledge received
Data Sent 012345678901234567890123456789 Acknowledge received
Data Sent abcdefghijklmnopqrstuvwxyz Acknowledge received
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Acknowledge received
Data Sent 012345678901234567890123456789 Acknowledge received
Data Sent abcdefghijklmnopqrstuvwxyz Acknowledge received
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Acknowledge received
Data Sent 012345678901234567890123456789 Acknowledge received
Nano IoT serial window for RX
Data received accfggglmoonoooxy{{~|}
Data received 89;;>???<=89;;>???<=89;;>???<=
Data received qssvwww|}~xy{{~|}
Data received accfggglmoonoooxy{{~|}
Data received 89;;>???<=89;;>???<=89;;>???<=
Data received qssvwww|}~xy{{~|}
Data received accfggglmoonoooxy{{~|}
Data received 89;;>???<=89;;>???<=89;;>???<=
Data received qssvwww|}~xy{{~|}
Data received accfggglmoonoooxy{{~|}
Data received 89;;>???<=89;;>???<=89;;>???<=
Data received qssvwww|}~xy{{~|}
Data received accfggglmoonoooxy{{~|}
Data received 89;;>???<=89;;>???<=89;;>???<=
Test 4: Swapped one Nano v3 for a Nano IoT 33. Set IoT to TX.
Nano IoT serial window for TX
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Tx failed
Data Sent 012345678901234567890123456789 Tx failed
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Tx failed
Data Sent 012345678901234567890123456789 Tx failed
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Tx failed
Data Sent 012345678901234567890123456789 Tx failed
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Acknowledge received
Nano v3 serial window for RX
SimpleRx Starting
Data received ABCDEFGHIJKLMNOPQRSTUVWXYZ
Data received 012345678901234567890123456789
Data received abcdefghijklmnopqrstuvwxyz
Data received ABCDEFGHIJKLMNOPQRSTUVWXYZ
Data received 012345678901234567890123456789
Data received abcdefghijklmnopqrstuvwxyz
Data received ABCDEFGHIJKLMNOPQRSTUVWXYZ
Data received 012345678901234567890123456789
Data received abcdefghijklmnopqrstuvwxyz
Data received ABCDEFGHIJKLMNOPQRSTUVWXYZ
Data received 012345678901234567890123456789
Data received abcdefghijklmnopqrstuvwxyz
Data received ABCDEFGHIJKLMNOPQRSTUVWXYZ
Test 5: Change the SPI speed and repeat Test 3 and 4. Results are same as 3 and 4 were.
Test 6: Repeat 3 and 4 with another Nano IoT. Same results are original Arduion for tests 3 and 4
Test 7: Using IoT as TX to IoT as RX.
TX serial output
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Tx failed
Data Sent 012345678901234567890123456789 Tx failed
Data Sent Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Acknowledge received
Data Sent 012345678901234567890123456789 Tx failed
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Tx failed
Data Sent 012345678901234567890123456789 Tx failed
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Tx failed
Data Sent 012345678901234567890123456789 Tx failed
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
Data Sent ABCDEFGHIJKLMNOPQRSTUVWXYZ Tx failed
Data Sent 012345678901234567890123456789 Tx failed
Data Sent abcdefghijklmnopqrstuvwxyz Tx failed
RX serial output
Data received qssvwww|}~xy{{~|}
Data received accfggglmoKNOOOXY[[^__|}Data received 89;;>=??<=89;;<=7?<=89;;>???89
Data received qsstwww|}~xy{{~|y
Data received accdegglmoonoooxy{{^___\][
Data received 89;;<=??<=813;>???<=89;;>???8=
Data received qccfwww|}~pyss~xy{
Data received accfGgGLIKKNoOOXY[[\}|}
Data received 89;;<=??<=01;3>???<=89;;>???<9
Data received qssvwww|}l}ooxy{{~|}
Data received accfggglmoonooopqs{~_XY{
Data received 89;;<???<=89;3>7?7<=89;;>???89
Data received qssvwgwl}o|}xy{s~ww|}
Data received ACCFGGGLMoolmooxy{{~|}
Test 8: Switch roles of the IoTs, what was RX is now TX and vice versa. Results same as Test 7