Some people have tried this which might work....use a 13 character password.
Sounds odd but some devices can be a bit "picky" when it comes to connecting to things.
If not, I definitely do not recommend turning all encryption off. You might want to try going through the manual settings route and input all entries yourself (just to make sure they're all correct).
Finally, try changing your router to broadcast on channel 1, 6 or 11 (the only truly 'discrete' channels ---- all the others overlap with adjacent ones). Again, a long shot but worth a try.
Here is an explanation of error 51300 btw
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