R7800 losing internet after modem reconnection

[mrezrider]

My ISP has Asus modem/router that I still use while it has/routes IPTV .. R7800 is connected and in router mode .. all is good until modem reconnects every 24h .. after that R7800 gives wifi .. says internet is ok .. but no worky worky .. I reboot R7800 and than it gives internet to all devices connected .. what could be the problem? why on modem reconnect .. r7800 looses abilty to give internet .. dns stays the same ip of r7800 stays the same .. nothing changes .. just maybe outer IP from ISP .. routers is 192.168.1.1 modem is 192.168.5.1 .. router gets 192.168.5.47 ip from modem ..fw is up to date

[mrezrider · Accepted solution]

I have installed Voxel fw .. same as netgear but newer versions .. I dont think that made it much better 

But I have added is 3rd DNS server in router settings .. I have two Googles and 3rd is modem 192.168.5.1

and now after modem reconnect I still have internet .. but delay on page load is few seconds, noticable .. so I guess router uses 3rd dns, modem address .. after I reboot router I have much faster load of web .. there is no pause on load .. starts to load after 1 sec .. 

hmm .. that is what I have now .. really puzzled .. 

[mrezrider]

update

today again same thing .. on modem reconnect no internet
BUT
on iPhone that is connected to R7800 some apps have internet after reconnect
like TuneIn Radio and Facebook app, Whatsapp .. others like web/safari, mail, gmail do not work .. I hope this helps ..

[pec967]

My guess is that this has something to do with your "double-NAT" configuration. I would either change the configuration of the modem/router to modem-only, or change the R7800 to AP mode.

[mrezrider]

I also think something about NAT, disabled NAT/UPnP on modem.

Netgear support wrote to find MTU .. and I think mine is 1460, so I set that up.

modem works as a router also .. but is ISP special fw .. very few options to set .. 

I will try to turn off what I can on modem .. and keep R7800 as router

disabled NAT/UPnP on modem

set R7800 address as DMZ on modem

turned off all firewalls on modem

kept DoS protection ON on modem

set MTU 1460 on R7800 (modem doesnt have that option)

[mrezrider]

did all above .. same problem .. 

disabled DHCP on modem

made factory reset on R7800

manualy set everything .. 

waiting tomorrow

[pec967]

Disabling DHCP on the modem/router is not necessarily the same thing as disabling the router portion of the modem/router. Most ISP's will have instructions on their web site, or via call-in tech support, on how to disable the routing function of a modem/router.  Are you sure you disabled the router portion of the modem/router? Does the R7800 now have the external IPv4 address rather than a private IPv4 address?

I have had flaky behavior with the R7800 after a firmware update  if I did not do a reset and then manually enter all the data again, but it sounds like you have done that.

If you decide you have disabled the router in the modem/router, you might try the alternative option of configuring the R7800 as an AP and turning on the router mode again in the router/modem. The R7800 manual describes how to set it up as an AP.

[pec967]

Another comment. If you end up going back to having the router enabled in the modem/router, I would restore all the settings you changed in the modem/router back to their original values, e.g., leave NAT on, turning off UPNP is fine, don't put the R7800 in the DMZ, and restore the firewall.

As far as the MTU setting in the 7800, 1500 is the usual value unless your ISP uses PPPoE in which case it is 1492. There are more exotic cases with VPN.

[mrezrider]

thank you ..

i am sure that modem is still router .. r7800 still has local IP assigned from router but static now .. I want to use my R7800 as router ..

I dont think I can turn off router on modem while it has IPTV STB connected to it.

My connection is PPPoE and my MTU for my ISP is 1460. I tested it with ping and dont fragment command.

[pec967]

My recommendation is to set the R7800 to AP mode and to restore the original settings in the modem/router.  As I always tell the students in my networking class, NAT is a necessary evil in the IPv4 world, but double-NAT is stupid 🙂

[mrezrider]

today .. same thing .. lost internet on most of devices .. after modem reconnect .. 

one MBA was able to surf the web ? other devices no net .. 

there is nothing I can do .. i did all 🙂

I turned off before .. as stated in previous posts .. DHCP on modem .. 

and now IPTV doesnt work as it needs DHCP .. 

so that is ON again on modem now .. 

I guess I could switch to AP mode only .. but whats the point of having 250EUR router in AP mode 🙂 .. 

[pec967]

I replaced my Linksys EA6900 with the R7800 not because of its routing performance, but because of its wireless performance and range. If you look at the SmallNetBuilder.com router rankings, https://www.smallnetbuilder.com/tools/rankers/router/result/2538-netgear-r7800?testmethod=35, the R7800 has a mediocre HTTP score when compared to routers based on newer chip-sets, but its wireless performance and range are top notch. I now have a strong 5 GHz signal and high throughput throughout a two-story house and in the backyard. The R7800 is also very stable, which is the top thing on my list in choosing a router.

The bottom line is that I think you are getting your money's worth running the R7800 as an AP.

[mrezrider · Accepted solution]

I have installed Voxel fw .. same as netgear but newer versions .. I dont think that made it much better 

But I have added is 3rd DNS server in router settings .. I have two Googles and 3rd is modem 192.168.5.1

and now after modem reconnect I still have internet .. but delay on page load is few seconds, noticable .. so I guess router uses 3rd dns, modem address .. after I reboot router I have much faster load of web .. there is no pause on load .. starts to load after 1 sec .. 

hmm .. that is what I have now .. really puzzled .. 

[pec967]

I would remove the two Google DNS servers and just use the IP address of the modem/router in teh R7800 and see if this fixes the problem. Alternatively, just configure the R7800 to use the DHCP configured values.

[mrezrider]

did that ..

I dont see a connection between modem reconnect and DNS set in router

but I guess now should be ok ..