G.INP switch-on causing dramatic speed drop

I have noticed that G.INP has been switched on (for downloads) on on my connection today with dramatic effect. Download speed is changing frequently and often dropping to half or less of the stable speed ( 36mbps) that I have enjoyed for the 2 months since FTTC was enabled. SNR and attenuation have not changed significantly. I am about 1200 metres from the Huawei cabinet and my modem/router is Billion 8800NL.

Is this immediate effect normal and will it settle down in a few days?

G.INP might impact on connection speed, but should not be behind highly variable speeds during a test, what do speed tests look like i.e. supply a link to the result from http://www.thinkbroadband.com/speedtest.html

G.INP are suppose to increase in your downstream sync rate, not reduced! Try power down Billion 8800NL for 31 minutes and power back up and this may resolved for u. It's happen to me once.

Thanks for the replies. G.INP seems to have settled down now and I am back to the pre-G.INP speed. Hopefully, it will stay that way. In view of the distance to the cabinet I was very happy with speed before G.INP.