On a network that was working fine, I just replaced a normal (dumb) 8 port switch with a TP-Link TL-SG2008 Desktop Smart Switch. I installed it because I wanted to use SNMP with it to see real time transfer rates.
Before installing, the only thing I did was change the IP address, enable SNMP, and add the public community. (I know it's not recommended to use "public" and I will change it once I get it all working.)
SNMP works just fine. I have tried disabling it also so fix the following problem. I makes no difference.
Now I have unusably poor connectivity to two Ubiquiti Unifi Access points through the device. I have tested and found half the pings dropped to the Unifi's even from PC's connected to the same switch. I have tried restarting everything multiple times.
All devices other than 192.168.0.89 and 192.168.0.93 work fine. The switch in question (192.168.0.11) is just above JOHN-PC ( the red rectangle). The swtches immediately before 192.168.0.89 and 192.168.0.93 are just normal consumer 5 port dumb kind.
Here is my network map.