Just moved into a new place, 90 year old place converted into 2.

3 Jackpoints, sky, bedroom, and i assume the main.

Connected to new unbundled exchange with 1.4mbits when i plugged in and checked, cool.  This is at 2pm.

Caught up with my linux distros with perhaps a couple of discs over the 5 hour period but nothing bad, speed had dropped to 1.2.  I think meh and carry on.  This is 7pm.

By 10pm that night lots of discs and speed dropped to 200kbit.  If i drop the modem and wait (i assume the wait bit is the working bit) it might go back to 1mbit.  Lots of RX crc errors.

Slept, up at 630ish check speeds, 600kbit.

Speed back up to 1mbit once the sun is out.

Did a reccie around the house found the demarc which looks like an inside one setup under the eave outside with no front panel on it.  traced that back to the sky and bedroom jackpoints.  tested both points, no adsl light.  K.

rang isp logged a fault. waiting........

same deal last night progressively worse later in the evening and early morning, once the sun is out for the day everything is as fine, still a few rx crcs but still usable.

Is this a dew point related kind of issue?  anyone had one of those before?  I am beginning to think it might be an insulation fault on an outside exposed bit of cable, time will tell though.