Cable Forum - Dodgy Internet Connectivity + Default Gateway

Howdy guys :)

I've been having some problems with my NTL 2Mb Cable connection, and has been happening for quite some time. Basically, it keeps timing out for a couple to several seconds. This in turn can happen every few seconds to every couple of minutes. The actual problems is causes are varied. Generally, when I'm not doing anything that requires internet, the connection more or less behaves itself although MSN Messenger will without a doubt disconnect at some point for some unknown reason.
1. When downloading from Newsgroup servers the transfer will happily max out at around 250kb/s but will just drop to zero after a minute or so. The connection is 'dead' for around 10-20 seconds before the transfer bounces back up to max again. Throughout this dead period, web pages will not refresh/connect and there will be no response from game servers etc.
2. During online gameplay, pings often fluctuate to triple figures, a year ago this connection was rock solid and pings were at a superb 15-30ms! Now, within half an hour, I can put a hefty sum that I will be disconnected from any game server, and I will rightly guess it is due to these timeouts peppering my connection.

Before, I had an old-skool Terayon TJ something-or-other modem. After a BAJILLION modem restarts and after 2 very long phone calls to a very time-wasting yet highly amusing NTL Broadband Tech Support, they agreed to send out an engineer because (as usual) there was nothing wrong from their end to my modem. The usual spyware/firewall/antispyware rubbish was chinwagged. I have had the Terayon modem replaced with a horizontal semi-transparent small-ish blue one (not sure what make/model, all the sticker says is ntl: 250!) and although the problem is not as bad as before, it still occurs, somehow it seems more problematic in the evenings. He also fitted an attenuator but was as confused as me as to why the problem hadn't solved itself. When I have my PC at university, I'm connected wirelessly to BT ADSL and I have no problems there! This pretty much stresses that it must be a problem with the NTL line here but I wanted to see what exactly was causing the problem. Here are signal levels just in case:

Cable Modem Downstream 15-01-06 18:16
Downstream Lock : Locked
Downstream Channel Id : 2
Downstream Frequency : 402750000 Hz
Downstream Modulation : QAM64
Downstream Symbol Rate : 5056.941 Ksym/sec
Downstream Interleave Depth : taps32Increment4
Downstream Receive Power Level : -5.8 dBmV
Downstream SNR : 35.0 dB

Cable Modem Upstream 15-01-06 18:17
Upstream Lock : Locked
Upstream Channel ID : 1
Upstream Frequency : 33584000 Hz
Upstream Modulation : QPSK
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 49.0 dBmV
Upstream Mini-Slot Size : 2

This may so far it sounds like it belongs to the NTL broadband support section but the following section I think fits in this department: (moderator can move/duplicate this post if he wishes ;))

I have 2 PCs and a laptop sharing the connection through a Linksys BEFRS41 ethernet router. Each one in turn connected alone to the modem doesn't rectify this problem. I've been testing my PC for any errors in TCP/IP connectivity and doing a series of ping tests in the cmd. The usual ipconfig, pinging local hosts etc are fine from what I can see, but the first major problem comes up when I try and ping my default gateway.

Pinging 81.XXX.XX.254 with 32 bytes of data:

Reply from 81.XXX.XX.254: bytes=32 time=225ms TTL=254
Reply from 81.XXX.XX.254: bytes=32 time=126ms TTL=254
Request timed out.
Request timed out.

Ping statistics for 81.XXX.XX.254:
Packets: Sent = 4, Received = 2, Lost = 2 (50% loss),
Approximate round trip times in milli-seconds:
Minimum = 126ms, Maximum = 225ms, Average = 175ms

I've done a several consecutive runs on each networked PC in turn, and not one has completed with 0% loss. It's always either 25%, 50%, 75% or 100% loss. What is the nature of not being able to ping the default gateway sucessfully? What can be done to mend this? I'm wondering if this is the root of my problems :dozey:

Cheers, Simon