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Can an ethernet cable on a reel be used at full speed?

I bought 100m of relatively cheap CAT6 FTP ethernet cable on a reel. For testing purposes, I installed RJ45 jacks on the ends to check whether it can be used at 1Gbps. Observing the lights on the switch revealed that the link fails at 1Gbps a few times and after a short while, it falls back to 100Mbps. At that speed the link seems to be reliable.
Is it possible that the same cable would work at 1Gbps when used in a straight line without the reel which introduces some inductance?