I have a new install of Ubuntu MATE on a dedicated server in my home. It is connected to my router via ethernet. It receives the typical internet speeds I would expect of from a computer on my network, both upload and download. As a server, connections outside my network to it are fast and reliable; I use it for Plex and Foundry VTT, and have had no complaints there.
In spite of this, if I attempt to connect directly to the server over my home network, the connection is completely unusable. It does not matter the device used. From my Windows PC (connected to the same router via the same type of ethernet cable), while I can access the webpages for Plex or Foundry, they load incredibly slowly, with some elements never loading in. I can access them perfectly fine if I put in my external IP address, but this seems absurd. Trying to remote into my desktop via various means (including XRDP and VNC) yields similarly undesirable results: either connections so slow and low fidelity that seemingly nothing can be accomplished, or just a black screen.
Far more of a pain point is trying to connect to the server on my phone while on the same network. For example, the Plex app knows I am on the same network and tries to help me by directly connecting. However, this results in it either insisting the server is offline or that my libraries have no content. Things operate fine only if I disconnect from my WiFi and use data.
This is ridiculous. Does anyone know what could be causing this?
