Help! My installation keeps disconnecting

Installation
1

I have HAOS installed to an old Lenovo ThinkCentre. It runs absolutely perfectly in itself. Connection to my network is via a wifi to ethernet device. All fine for about four years. Since I changed internet providers and got a new hub (SkyMax), the connection has become highly unreliable. It runs for a day or so, and then becomes inaccessible. Sometimes restarting the server is enough to fix it; sometimes I need to restart the hub. So far, I’ve tried the following remedies:

  1. assigning static ip addresses to HA and to the wifi/ethernet device
  2. a fresh installation of HAOS
    Neither have made a difference.
    Also though the app is currently working, the hub says HA is offline.
2

Even though you may have had it working that way for a long time, connecting your server using WiFi is not recommended. Can’t you plug your server into your hub using Ethernet?
What is the current IP Address for your hub, and for your HomeAssistant device?
Do you have both 2.4Ghz and 5Ghz using the same SSID?
What other devices do you have connected to the same hub?
What model is your Lenovo, the WiFi to Ethernet device, and the hub?

3

Is your new ISP sending your DHCP to it’s own server? My Centurylink did that, it drove me crazy.