AT328 reset while switching on any home appliances

Job ID: 31954389

Budget: ₹100 – ₹400 INR

hi there
i have a AT328PU / Arduino UNO with just the crystal and 10k pullup on the reset there is no relay or any load connected to it
i am using a 5v smps and have tried a HLK05 module also

while i switch on any appliences in home (anything on the same 230v power line that of the arduino SMPS input) the arduino restarts

i can see a drop in the voltage(5v power) (Oscilloscope graph attached) while appliences is switched on. but this i get in all the SMPS i have tried (20 of them)

i have even tried connecting till 2200 uf/ 4700 uf capacitor to the arduino 5v pin

can any one suggest what the problem is??