Dissapearing DNS? after replacing Netgear with TP-Archer D2

[#1]

Hi,
have just replaced my trusty DGN300 Netgear modem/router with a TP-Archer D2 modem router. Apart from problems with the initial "autoset up" not working (did the manual setup), i have a unusual problem.
Everything appears to be working fine all indicators are showing correctly, including ADSL and Internet, however overnight (well to be accurate after overnight twice now) although indicators are ok and modem stats are fine I seem to have lost all contact with the DNS servers. This must be a problem with the modem setup but it has got me really stumped. If I do a soft modem reboot from within the modem tools I can access everything fine.
I had a quick look at the WAN settings (see below) and the only thing that looked slightly odd was the IP MASK  which I have underlined
pppoa_0_38_1_d PPPoA 0/38 IPv4 217.39.117.40/32 195.166.130.205 212.159.6.10 212.159.6.9 Connected
any thoughts please.
Ian

[#2]

Hello again folks,
still having problems but seem to be making some progress  :-\.
I listening to BBC radio catchup this morning when suddenly lost Internet.
Checked out router and found ADSL and Internet indicators both solid ON.
Found some diagnostic tools on router management page and did a "Test for Internet" which produced the following results :-
xDSL sync                            OK
ATM OAM segment ping    OK
ATM OAM end to end ping  OK
Test PPP server conn.        OK
Test Auth. with ISP              OK
Test assigned IP addr.      OK
Ping default G/W                Fail
Ping primary DNS server  Fail
Test DNS root                      Fail
NCSI                                      Fail
so I guess this means my "disappearing DNS server" is really down to loss of G/W? Which in turn is down to Plus-net?
My profile has dropped over the past few days but I guess that is down to the number of modem resets I have been doing to try to resolve this problem.

[#3]

I don't think there's anything wrong with the IP mask. As you only have a single public IP address, then the mask specifies all 32 bits of the IP address. If you had a small range of public IP addresses, then the mask might be /30.
A simple way to determine if the issue is with DNS or more general lack of Internet connectivity, is to open a command prompt and try pinging an easy to remember IP address such as:
ping 8.8.8.8
ping 4.2.2.2
If you don't get any ping replies, then it's not a DNS problem, it's a more general lack of Internet connectivity. I wouldn't rely on the router's diagnostic tools too much, if the firmware is buggy, then the diagnostics might be just as buggy. In some TP-Link firmwares, the "DNS root" test was broken and would always fail, even when there's nothing actually wrong.

[#4]

Hi ejs,
thks for feedback.
Lost internet again whilst looking at your posting.
Followed your advice with the following results :-
C:\Documents and Settings\Ian>ping 8.8.8.8
Pinging 8.8.8.8 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
C:\Documents and Settings\Ian>ping 8.8.8.8
Pinging 8.8.8.8 with 32 bytes of data:
Request timed out.
Request timed out.
Reply from 8.8.8.8: bytes=32 time=28ms TTL=56
Request timed out.
Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),
Approximate round trip times in milli-seconds:
    Minimum = 28ms, Maximum = 28ms, Average = 28ms
C:\Documents and Settings\Ian>ping 8.8.8.8
Pinging 8.8.8.8 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Reply from 8.8.8.8: bytes=32 time=29ms TTL=56
Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),
Approximate round trip times in milli-seconds:
    Minimum = 29ms, Maximum = 29ms, Average = 29ms
C:\Documents and Settings\Ian>ping 8.8.8.8
Pinging 8.8.8.8 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Reply from 8.8.8.8: bytes=32 time=29ms TTL=56
Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),
Approximate round trip times in milli-seconds:
    Minimum = 29ms, Maximum = 29ms, Average = 29ms
C:\Documents and Settings\Ian>
and then did another router check with this result :-
Test Internet Browsing

  Test xDSL Synchronization Pass
  ATM OAM Segment Ping Pass
  ATM OAM end to end Ping Pass
  Test PPP Server connection Pass
  Test authentication with ISP Pass
  Test assigned IP address Pass
  Ping default gateway Fail
  Ping primary Domain Name Server Fail
  Test DNS Root Fail
  Network Connection Status Inspect(NCSI) Fail
Diagnostics Complete
So again looks like some Gateway problem?
I have now reconnected via my old Netgear router, after nearly 5 days of dropping internet. This will hopefully prove things one way or the other.
cheers, Ian