I have a gdbserver on a target, that I launch like gdbserver :2345 /bin/ls. Next I am connect a gdb from a host, and trying issue next commands:
gdbserver :2345 /bin/ls
In order to check which architecture your GDB currently support (those you can have in a set architecture command), just type:
set architecture
(gdb) set architecture
without any arguments... As simple as that. Otherwise, you'll probably need a cross GDB, as mentioned by @drbank0.