@CircusPeanut I had the issue before updating to v11.1 so I don't think it is caused by v11.1
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ERROR: AcceptToMemoryPool : nonstandard transaction: scriptpubkey
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ERROR: AcceptToMemoryPool : inputs already spent
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ERROR: AcceptToMemoryPool : free transaction rejected by rate limiter
All of these error messages may be wrong. I was getting multiple different issues on my test cases.
I think scriptpubkey was for unnecessary 0x00 padding (a different malleability issue).
I'm pretty sure the ERROR for Low S violation in 0.11.1 is:
ERROR: .... Non-canonical signature: S value is unnecessarily high
How many utxo's are in the wallet? it may be failing due to being to large of a tx in kb. You say you have been mining for a year and havent moved any. Im assuming you have a hefty build up of utxo's. Try sending multiple smaller amounts and see if they go through. If you know your average utxo size try sending that * 100