Engineer Visit - Do I have to remove my own equipment?

[#1]

Hi,
I have a Engineer's visit booked in for Tuesday. I'm currently using an ASUS DSL-AC68U vdsl modem/router. Do I need to remove this and put the old white box and separate router in again for the visit or are we ok to use our own equipment? My modem / router has been rock solid. Over 25 days of up time when I initiated a firmware upgrade which obviously dropped the line. Currently its up nearly 14 days.
Problem was my line appears stuck. I was syncing higher than the BT had as my line rate and my line rate never adapted to changes in my sync speed. Indeed in a recent test my download speed was marginally higher than the line rate BT had for my line. My line on the Plusnet side is showing a Line Rate of 78Mbps which well above what my line will support. Hence the reason for the visit. BT wants to investigate.

[#2]

Wouldn't it have been safer to go back to the Openreach modem and separate Plusnet router, and seeing if that fixed the problem, before reporting a fault and getting an appointment booked?

[#3]

I was complaining on this forum because my line seemed stuck. It was a Plusnet member of staff who opened up the fault, not me and I'm more than grateful that they did, and first I knew was when I got a message from Plusnet to my mobile to tell me to call in and arrange an appointment with them for a BT Engineer as BT had requested a visit.
In any case I wouldn't have the first notion how check if the issue is resolved or not given that BT have chosen to lock down the stats on their modems therefore how can I compare the sync rate of the modem with the line rate shown by Plusnet and the max achievable speed on BT wholesale?

[#4]

I use an ASUS DSL-AC68U Router Modem, and BT Engineers have visited with it connected. For some time I used the internal Modem because it gave me data that I cannot see otherwise, and because the Modem is very adjustable. Too adjustable perhaps? I could not find perfect settings or even the right settings, all who used the built in modem seemed to have various ideas of what was right. The data collected showed hours of no errors then tens of thousands some nights. I am sure that the port at my street cabinet reacted badly to my ASUS Modem and slowed me down.
After many months (2-3) I gave up with the internal modem and restored the supplied Huawei BT Modem configuring the ASUS as simply a WiFi and cable router. It has exceptional WiFi and router capabilities compared to the basic supplied unit.  My street cabinet is Hauwei also, and the two get on well. Speeds returned over a few weeks and remain very stable. I lose my connection data (I have tried to get it from the BT Modem without any success whatsoever), but I have a generally very reliable connection that seems to have speeds set in Cast iron. They waver hardly at all.
There have been two or three firmware upgrades to my Asus AC68U since I returned to using the BT supplied Modem, and maybe those have improved the modem functionality so that it talks better to BT cabinets, Huawei ones in particular, but based on previous experience, I doubt it and am reluctant to try. Why spoil what you have by taking a chance that could make it all go pear-shaped? I feel.  If I knew it would work, I'd give it a go, but I bet that it won't.

[#5]

@andun84
OK you wouldn't be able to see the VDSL2 line rates nor any other stats, but you could see if the BT IP Profile ever updates, and Plusnet support staff could get the line rates from the tests they can run, which could be compared to the IP Profile.

[#6]

Ok I guess I'll give it a shot though I'm not sure that I can get the call cancelled now as I have to give 48 hours which I bet doesn't include weekends so for Tuesday morning I may be too late now to do anything anyway.