Mate gui network set-up

[joehenley8100]

Hi,
Doing some firewall set up and testing -- LM 21.2 Mate. The test PC is connected to a Unifi smart switch. The test requires me to change the IP of the test PC 5 times (I have 5 vlans in the overall network). There are two ways I've tried to change the test PC's IP, both start with accessing the switch and setting the switch port to the vlan I'm going to be using. Then I can either set the PC to the "default, use dhcp" network setting or I can set it to a static IP (within the desired VLAN). And from either, I reboot the test PC. If I use the method of set switch port => set PC to default/dhcp => reboot PC, I get good, predictable results. If instead, I use the method of set switch port => set PC to specific IP (within the desired VLAN) => reboot PC, I get questionnable, unexpected results. Subsequent tests show the first method results are correct, the second method's results are incorrect.
Any thoughts as to why? Is there something going wrong in the gui which I use (Mate) to set the static IP? Is there something about the PC getting the "desired" IP info from the switch's dhcp which makes a difference? Are there some PC or router tables which aren't getting reset in a timely fashion? I'm stuck.
Suggestions appreciated!
Joe Henley