What exactly is going on with my connection?

[#1]

Generally the internet connection I receive has been good. Youtube videos load quick, downloads are not too bad, webpages load pretty good. But. But when I go to play some games online, it's ALWAYS 50/50 whether I'll be to play an hour or two with no lag. I used to live it with (been with Plus Net for maybe 3 years or more now)... but now it's really getting annoying. I've tried all those "tips" to get a consistent ping but...but they never worked and now it's just my connection is more erratic than ever. 

For example, when I play Rocket League on Steam, I'll join a game and it'll show 30-50 ping. Great! Then it will jump to 200, then 600 and finally 999 where it disconnects me. (I should point out that every other online game over the years that I have been with PlusNet, have been like this. As I said, I'm used to get an hour of good ping then 23 hours of unplayable ping.) I can join other games endlessly and will still lag. I've tried rebooting the Modem Router (I know not to keep rebooting over and over in a short space of time) but nope still lagged. It used to be I could get an hour of gaming before the ping problem would rear its head and I was fine with that. . . 

P.S I upgraded my Modem Router to a fancy TP link one as there is a lot of devices connected to the modem via Wi-Fi in this household and this has neither improved or made it worse.

Thanks.

[#2]

Are you sure you don't have anything uploading in the background, Itunes, Iphoto, Google Drive Sync, cloud backup etc?    It's really easy to max out the upload path on ADSL, and unless you have some clever prioritisation configured in your router this will hurt latency for everything.

I also experienced similar issues which were related to upload, but not even when maxing out my connection, I had episodes where latency would shoot up as soon as upload reached 90 or 100K (around 25% of capacity).   That must be some sort of queuing or traffic engineering issue within Plusnet, but I had no luck getting them to acknowledge or even understand the issue let alone investigate or fix it.

So in your shoes I'd keep a close eye on upload data rate, and see if there's any correlation with the variable latency.

If your router supports SNMP you could run PRTG to monitor all this, and set a couple of ping sensors to log latency,

[#3]

I can't see any programmes silently uploading. I ran Resource Monitor to see which programmes are using internet and unless I'm on Chrome, only Steam and some system programmes are using the internet and only use a little of it. 

My Modem Router does allow SNMP, I have enabled it and I am going to set up SNMP. 

In the mean time, this may just be a coicidence but I purchased a Plus Net static IP, rebooted my Modem Router and booted up Rocket League and I got a steady 28 ping. . .

[#4]

Do you have a note of the previous addresses where you saw issues?   Just wondering if they were from the ranges that some see as non-UK, and whether it could be anything to do with other ISPs routing to those addresses.

Alternatively has your path changed, do you have traceroutes from before and after?