@TheAutisticGamer sounds like poor wifi signal. the pi’s wifi antenna isn’t the greatest. It’s just enough to to work, but Depending how far your Wi-Fi is , how many walls it has to go through, how much other radio signals nearby causing interference, ect ect, can effect signal strength. Try using a 2.4ghz instead of 5ghz as they are more robust, and can travel further though walls, ect. easier.
Also it’s not dhcp failing. Even if your DHCP server failed, your pi would still keep its IP address as well whatever the other device on your network. It’s just any new devices won’t get a new IP address.

This has been resolved and the answer is on this thread that I referenced earlier.

So the plot thickens...

Today, after weeks of working from home, I seem to be having massive WiFi issues with my laptop. It’s been perfect literally up until this morning.

So I ran a WiFi scanning app and it turns out one of the neighbours have cloned our WiFi. So my laptop was connecting to the dodgy WiFi instead. Now this isn’t the exact same issue, but it all seems connected. I’ll investigate further. Maybe the RasPi 3 somehow has a preference for my WiFi and the Pi4 for theirs? both are just configured using SSIDs so it’s not like I’m entering the details any differently.

I'm going to change the WiFi details and see if it fixes the issue, or if it's just a massive coincidence.

@hellska said in Dynamic IP address 'not stable':

The power supply is 2Amp, is it weak for the WiFi to function properly?

@hellska It probably depends on what else you have attached to you RPi, but the specs for RPi3 say 2.5A is recommended.

Your issue reminds me the behavior of my RPi1 with an external Wifi dongle. I never confirmed it was caused by insufficient power, but the fact was I had a poor 1.5A power supply back then. Using scp (which is consuming bit of CPU btw) was causing my Wifi to disconnect many times.