Cannot hold an internet conection; disconnects requiring factory reset of router

[TanyaC]

Sorry, this is going to be long.

I have an ASUS RT-AC88u connected to a FTTP 100/20 connection via an NBN NTD.
A month ago the connection became unstable and eventually disconnected. After going through several checks I found that doing a factory reset on the router and then restoring my configuration fixed the issue.

Yesterday the same thing happened, however, this time I cannot maintain a connection. It seems whenever I make any change to the router configuration it disconnects, or maybe that's just a coincidence as I have extensive DHCP reservations and firewall filters that take quite a while to key in manually.

So I connected a cable from PC to NTD direct and the connection is stable, which seems to indicate that this is a CPE issue.

So I replaced the ethernet cables from the router to the NTD and router to switch. I power cycled everything. I've upgraded the Merlin firmware and then downgraded it.
None of that worked so I put in my spare ASUS RT-AC68u and it has exactly the same issues. Will connect for a while then disconnect.
Typically once it disconnects it stays disconnected until I factory reset the router, although while I was talking to my ISP it dropped and reconnected a few times.
I am also now getting certificate errors in my Firefox. The router defaults to 192.168.1.1 but I have a server on that address so I always change my router to 192.168.1.254.
The ISP says they can't escalate the issue because a direct connection from PC to NTD is stable and speeds are good.
The router connects to a smart switch via cat6 and then via internal cat6 through the walls to an upstairs socket. There are several sockets upstairs, so I've tried all of them and the problems are the same.
Could a switch cause the connection to drop (It's a netgear GS108T-V200, and I don't have a spare).

I'm going to factory reset the RT-AC68u and leave it alone and see if it can hold a connection to prove that it's not be updating the configuration that's killing the connection. I'll also isolate the switch to see if that's causing it.
Could these certificate errors cause the connection to drop? ( I get this in Firefox when I log into the router).

Other than that, I'm out of ideas. I don't know what else could be causing this.

 

[TanyaC]

Isolating and replacing switch did not solve the problem.
Neither did leaving the router at factory defaults (excluding the configuration required to connect to the ISP).

 

[Tech Junky]

Some photos and logs would be helpful to see what's happening.

 

[degrub]

it would seem that the only thing constant (ie the problem did not follow a specific device or cable) in all of the above is the wall connections, wall cabling, and possibly something central (in wiring closet perhaps ? ) like another switch (wiring closet).

a sketch showing your physical layout and all devices would be helpful.

 

[TanyaC]

Sorry, I should have thought to post a diagram. I will do that now.
Although, I have found the problem

There seems to be a fault on UNI-D2 on the NTD. After many objections from the ISP I got them to switch me to UNI-D1 and connection is now fine on all routers tested.

An issue I had some years ago was the fiber terminator seemed to have gotten dirty. Cleaning it fixed the problem back then so I tried cleaning it again.

I should have thought of this earlier as the same thing happened to me about 6 years ago. NBNCo. came out and replaced the NTD at that time. I might end up going the same way. I figure if one UNI-Dx port is faulty, then maybe the others aren't far behind?

 

[Deleted member 82765]

Sorry, this is going to be long.

I have an ASUS RT-AC88u connected to a FTTP 100/20 connection via an NBN NTD.
A month ago the connection became unstable and eventually disconnected. After going through several checks I found that doing a factory reset on the router and then restoring my configuration fixed the issue.

Yesterday the same thing happened, however, this time I cannot maintain a connection. It seems whenever I make any change to the router configuration it disconnects, or maybe that's just a coincidence as I have extensive DHCP reservations and firewall filters that take quite a while to key in manually.

So I connected a cable from PC to NTD direct and the connection is stable, which seems to indicate that this is a CPE issue.

So I replaced the ethernet cables from the router to the NTD and router to switch. I power cycled everything. I've upgraded the Merlin firmware and then downgraded it.
None of that worked so I put in my spare ASUS RT-AC68u and it has exactly the same issues. Will connect for a while then disconnect.
Typically once it disconnects it stays disconnected until I factory reset the router, although while I was talking to my ISP it dropped and reconnected a few times.
I am also now getting certificate errors in my Firefox. The router defaults to 192.168.1.1 but I have a server on that address so I always change my router to 192.168.1.254.
The ISP says they can't escalate the issue because a direct connection from PC to NTD is stable and speeds are good.
The router connects to a smart switch via cat6 and then via internal cat6 through the walls to an upstairs socket. There are several sockets upstairs, so I've tried all of them and the problems are the same.
Could a switch cause the connection to drop (It's a netgear GS108T-V200, and I don't have a spare).

I'm going to factory reset the RT-AC68u and leave it alone and see if it can hold a connection to prove that it's not be updating the configuration that's killing the connection. I'll also isolate the switch to see if that's causing it.
Could these certificate errors cause the connection to drop? ( I get this in Firefox when I log into the router).

Other than that, I'm out of ideas. I don't know what else could be causing this.

I have read your post normally mind you should not give you problems take a good look that there is no conflict with any ip that you have entered again, it would be good to delete and leave for example what is strictly necessary I mean the IP of DCHP you should leave your computer your mobile and little else the rest let your router assign it automatically try not to have more than 10 reservations try to let it assign by itself also for many resetting the factory settings does not solve or try to return to the firmware you had before having said problem and not risk updating the firmware yes that brings you problems, wait a few months and try the following firmware or if it does not save all the configuration of your router, put the new firmware and load the configuration that you had saved so you will stop manually entering DCHP and other things... good luck

 

[TanyaC]

Excuse me?
All IPs are in one subnet, 192.16.8.1.x
All DHCP reservations are incremental.
All Switches are grouped together and the router is at the end.
How is that a mess!?
Or are you just having a dig at my diagram in general?