My Smart HUB reset the other day (middle of the day!!!) and came back with the new SG4B100021F4 firmware. That's when the problems started, I found:
The DHCP issues still have not been fixed. Can not assign a static address to a device
If you change a setting and select Save, it sits with the saving message at the top of the screen
Event log reports that the LAN DHCP server is active then inactive, then active again. This seems to go on for an age
I seperated the WiFi bands and tried to set the 5GHz name, the field auto-populated with the first letter of the 2.4GHz SSID and added a -5 to the end, but would not let me add anymore characters. Worked out that I could go backwards and add required SSID
Then after I saved the WiFi config, the config page came back with the WiFi switch displaying WiFi was OFF, but both SSIDs were available on the network.
I then decided to do a factory reset of the router and re-configured the settings. All of the above issues will existed after the reset.
SH6 is a major disappointment and needs a firmware update that resolves the real issues.