Posted this on the BT community forums but since discovered this site. What an excellent resource!
We have had BT infinity 2 (up to 78 Mbps) for nearly 4 years and since the day of connection until a month or two ago any speed test indicated we pretty much got the headline rate. Now seeing 58Mbps down and 14Mbps up. When it was installed the BT engineers gadget showed our line was more than capable for 80/20. Of late however I noticed some activity was a bit slower, especially my backups to Azure. Unfortunately I don't have any line stats to go back to.
From the info found on here I discovered we have a Huawei cabinet but a ECI modem so couldn't get stats. I've never used the BT Home Hub, preferring an Asus RT-AC68U for the past 2 years. I've acquired a HG612 from eBay and had that running a couple of days, installing the unlocked firmware. Since installing it I've had to disconnect the phone line once as the modem seems to run hotter than the ECI and I needed to move it for more ventilation, other than that the connection has been stable (and going back weeks the router logs don't show any disconnections).
I've got a better modem/phone cable on order but currently using standard flat cable the modem came with (don't think it will be twisted). Modem is connected direct to the NTE5 socket. Line is underground from the cabinet to the DP in the street and from the DP to the house. Distance from the house to the cabinet is about 200m as the crow flies but unsure how long a path the line takes. In the house the old master socket wasn't in a good position so the original line was extended by the engineer about 10cm into a new NTE5 master socket also into which there is a phone extension running from upstairs. I've made no changes to extensions or phone handsets since. No noise on the line to be heard when conducting a quiet line test.
With the background out the way I'm hoping someone more experienced than I might be able to shed some light on the possible reasons for the performance to have dropped?