Access Point issues

After struggling with getting started on Home Assistant, I have narrowed down my problem to access point issues. Here’s my story: Being new to HA, I installed HASSIO as a VM in virtualbox and began to have issues connecting to the UI. I switched to a RPi 3b Hassio, thinking it was VM or old computer issues, but eternal “loading data” and “connection lost” messages nearly drove me away from HA. Then, I discovered that my network is causing issues. I have a main router and an access point in the basement. The AP is set to only provide wifi and let the main router admin the DHCP. Depending on which SSID my laptop or phone is connected to affects my ability to connect to HA consistently: The main router SSID is inconsistent (and FRUSTRATING), but the AP SSID connection is pretty solid to HA. I think the AP is controlling all ethernet connections because no matter what port I plug into (all rooms of my house are wired via switch to the main router) my Windows Network Manager shows that I’m connected to the AP and if I have my phone or laptop logged into the AP SSID, then all is well with the HA UI. . . except I have to stay in the basement. My RPi is connected to the main router with an ethernet cable.
Am I missing something? My AP is not giving out IP’s (DHCP is disabled) and it is a tplink access point ONLY [not a router turned AP],
I’m hoping someone can see beyond the DHCP settings and help me know why HA UI works through my AP SSID, but not my main router SSID connection.