Broadband slows down, reset router ok for a while, then happens again

[Hawkmoon19]

Any advice? My Broadband is copper 50mbps download speed to router on the line. Usually fine but last two days in the hot weather (coincidence ?) Broadband speeds get slower and slower and then get massive ping spikes of over 500 on multiple devices. BT app speed test shows speed to router drops down to as slow as 3mbps direct to router. Affecting devices connected by ethernet and wi-fi so it's not a wi-fi issue as far as I am concerned, can't be neighbours' wi-fi interfering, got to be my line, roadside box or my BT Smart Hub 2 router. Online trouble-shooter from BT says no line fault/box fault so how do I troubleshoot my router, knowing it's not a wi-fi issue? What should I try to do? Basically what I see is that speeds slow down and ping starts spiking. You power down and reboot Smart Hub 2 and it's stable and fast for about 30 mins then it starts again to go slow and ping spike. 

[WSH]

Daft as it sounds, it is possible it is due to the heat.  Not only does that make the line expand and get longer, increasing attenuation, but the cabinets can over heat especially if there is a faulty internal fan.

There are people on here much more knowledgeable about this side of things that myself, so I’m sure someone will give you a better reply.

[Hawkmoon19]

Thanks well it reached 29C here in Surrey so I guess so. After the most recent reboot I looked at the router log and it has done a firmware update an hour ago and touch wood it appears stable now...maybe the fw update cured something

[rbz5416]

If you still have analogue phone then next time it happens, dial 17070 & select Quiet Line Test. The line should be near silent with no pops, clicks or crackles. if the line is noisy, report that as a telephone fault rather than broadband.

If the line is quiet then remove the faceplate from the master socket & use a micro filter to connect directly to the test socket behind. This isolates any internal wiring & the connections between the two parts of the master socket.

If still no joy, try replacing the router. Rather than battling BT I'd suggest buying on from Facebook Marketplace or similar for a few pounds. When you replace it, remember to also replace the PSU & DSL cable.

[WSH]

...a firmware update, you say?  Is that a Smart Hub 2?  In which case I'd be interested to know what the firmware number is.  Thanks.

[Hawkmoon19]

0.43.01.15019-BT

[WSH]

Ah, so there's a new version being rolled out.  Previous was v0.42.00.10167

Thanks for that.