OK, so here's my story. I have had PC2 since day 1 and haven't had any significant DC issues until yesterday. What changed? I switched Internet Service Provider.
I am connected on Fibre and was getting 50-60 Mbps down and 18 Mbps up and 15ms ping according to the OOKLA speed test on my phone. Going to the new ISP I have been getting as much as 94Mbps down and 20 Mbps up with 18ms ping. However, I do have a beef with them as at certain times of day it seems performance drops as low as 20Mbps down, but that's an aside.
So I go out to my man cave yesterday and try PC2 on my PS4, which is connected by a LAN cable to a power line extender which connects back to the router. I instantly realise I have disconnection issues with PC2 online lobbies. I struggle to get into rooms, and when I do get on track I get around the first 3 corners and then it DC's - just enough time to also get a sense that the force feedback feels really odd.
I have probably tried 20 times now and not finished one race. The only lobby that seemed stable was one where I was the host and about 5 other people joined me.
I have tried a number of tests to try and isolate possible causes. The tests include:
* firing up PC1 - first lobby, rock solid and completed the race no issue (points to a PC2 specific issue)
* resetting the power line extender, router and fibre network terminal
* swapping the new router from the new ISP back to my original router
* Using a 25m LAN cable to bypass the powerline extender and plug the PS4 directly into the router.
None of them has really made any improvement to the situation (although I did get furthest with the 25m Lan cable - needs some more testing). You could argue it is the new ISP that is to blame, but why does PC1 work with them? Is it possible PC2 and certain ISP's just don't get on? This doesn't really make sense to me - you are either connected to the internet, or you're not.
Something else I've noticed - when the PS4 is off and I connect my phone via wifi to the powerline extender and test speed, I get a figure similar to what I get when connecting via wifi to the router directly. But when I turn on the PS4 (connected by a wire to the power line extender) the speed test result on the cell phone drops significantly. It's as if the PS4 consumes bandwith, even if it isn't doing anything. Even the PS4 built in internet test shows the reduced speed. It's odd, but can't explain anything as presumably that has been the case all along, even when I had no connection issues in game.
So I'm not sure what do to. I still feel in some way it is the game at fault as PC1 works. I just can't really explain why things have changed with change in provider. I just hope they can therefore patch it. I can't easily go back to my old ISP as I have signed up for 2 years with the new crowd as we get a 50 inch UHD smart TV for free out of the deal, and even if I did go back, there is no guarantee this would fix the problems with PC2 anyway.
Just thought I'd share.
So next chapter in my story (in case it can help someone else):
I rang my new ISP from work this morning to complain about the variable (and low) internet speeds I was getting since switching to them. The person on the other end said they were going to change a few settings at their end but I really needed to be at home to sort it properly, and I should ring back after work.
I did ring back after work and explained to the new person what had been happening. I also mentioned for the first time that I was specifically having issues with disconnections from online gaming. She seemed to know immediately what settings could cause that from their end and noted that one of the things changed after my first call was one of these settings relevant to game disconnects and that it would need an ONT and router reboot to take effect.
So I did that and then set about testing internet speeds and online in PC2.
The important bit for us is that is has seemed to have made a difference to PC2. I won't say it's perfect - I have still had 1 in race disconnect, plus I have had 2 cases where I went to join a lobby and it immediately said I was disconnected, but I tried again straight away to the same lobbies and it went in fine and had no further issues. More testing is needed, but I would suggest from this that if you are having disconnection issues it is worth trying a call to your ISP to see if they can change settings to help. I now also recall she said if I still have trouble I can call back and there is another step they can take.
Other learnings I have made:
* I now seem to be getting lower pings (10ms) and faster downloads (75 -90 Mbps) on wifi devices connected to the main router, since whatever the ISP changed today.
* I am definitely getting a loss in speed across my powerline extender to the man cave. Generally I am only getting 30 - 50 Mbps on any device connected to the extender. This presumably was happening with my previous ISP but didn't seem to cause an issue.
* When I turn the PS4 on, which is connected to the power line extender by a LAN cable, the speed I get to my cellphone, connected by wifi to the same powerline extender, drops to about 10Mbps. Also, the built in speed test on the PS4 (which I don't entirely trust) also gives a speed of about 10 to 15 Mbps, which is pretty poor. I really can't explain why having the PS4 on (and doing nothing) should affect anything, but it does appear to.
* When I bypass the power line extender with a 25m cat6 lan cable to the PS4 I get up to 90Mpbs download, according to the PS4 built in internet check (which as I say, I don't entirely trust because it is quite variable, and sometimes gets an answer incredibly quickly).
* When I plug my wife's laptop into the main router directly with a 1m lan cable I get 8ms ping and 165Mbps

download speed. This point, combined with the 2 above makes me think part of my speed loss to the man cave is purely the distance.
Also forgot to mention that through most of today's testing, the family were watching Netflix in the living room, so that may have impacted some results.
So, looks like I will be burying a Lan cable out to the man cave. Then just some more testing on PC2 to see how much of an issue I still have. If it is too big I will contact the ISP again to see what the next step is...
I have my fingers crossed.