Unfortunately, this is a longstanding issue with no simple solution. We describe the issue in some detail in the docs, and you will also find some discussion around possible workarounds on various posts here (e.g. here and here) and on the GitHub forum (e.g. this one).
In your particular case, the issue is that the GL version is not supported, most likely because it’s trying to use GLX and GLX doesn’t (as far as I know) support OpenGL >= 3. These are the relevant lines:
WARNING: Application calling GLX 1.3 function "glXCreatePbuffer" when GLX 1.3 is not supported! This is an application bug!
mrview: [INFO] GL renderer: llvmpipe (LLVM 6.0, 256 bits)
mrview: [INFO] GL version: 2.1 Mesa 18.0.5
mrview: [INFO] GL vendor: VMware, Inc.
mrview: [WARNING] unable to determine OpenGL version - operation may be unstable if actual version is less than 3.3
For the record, mrview will attempt to run anyway regardless of these errors since in some cases, things seem to work despite the system reporting versions that shouldn’t work…
I’ve not been able to figure out the criteria that would allow mrview to run over a regular X11 remote rendering connection – even though I have seen it work. I think it’s dependent not just on the version of mesa installed on the remote system, but also what’s installed on the local system, and whether it determines that it can perform (software) rendering on the remote server or if it tries to use a more standard GLX connection with rendering on the local system (which won’t work AFAIK).
I wish I had a better understanding of these issues… But in the meantime, I’m hoping that Wayland will eventually make all these problems disappear (although it might be a while before we get there…).