Internet port (WAN) keeps "detecting". I am driving crazy!

[wharfedalemfm]

I had this same problem before, reported here

https://community.netgear.com/t5/Orbi/RBR50-no-internet-WAN-port-keep-quot-detecting-quot/m-p/155868...

Followed instructions in that post and the system works stable for 4-5 days and then I thought the problem was resolved. But it's NOT. It comes back!

Basically, the internet status reported at "BASIC"->"Home" is frequently "detecting". When it happens, there is no internet access. It can always back to normal. But this "detecting" happens so frequently it makes my internet unusable. 

Some info here: 

Same modem was working flawlessly with TP-Link router. Never need to reboot anything. 

Firmeware: tried both 2.1.3.4 and 2.1.4.10. Both times with hard reset and setup from scratch. Both times the modem was powered down for more than 5 minutes bofore new setup. 

Tried disable "DoS and port scan protection". Does not solve the problem

Tried "use computer MAC address". does not solve the problem. 

Extremely frustrated. I am not a newbie in terms of technical knowlege (Ph.D. in EE telecommunications). Netgear, please solve this problem. 

[wharfedalemfm · Accepted solution]

For the benefit of everybody. The "detecting" problem was caused by MTU size!

Default size is 1500, which is a hair too large. I changed it to 1492. Everything is running fine for the last week. No single disruption. 

I think this is ISP dependent. You can do a ping test to determine your MTU size. Just google it. 

[FURRYe38]

What is the Mfr and model# of the ISP modem/ONT? 

Cable or DSL ISP services?

[wharfedalemfm]

Arris SB6141 cable modem. ISP is Spectrum.

[FURRYe38]

I would contact NG support and ask about this. You may have a faulty router that needs to be RMAd. You seem to be one of few posting about this. Which leads me to believe after all you have done between FW versions and resets, the router needs to be relaced...

[wharfedalemfm · Accepted solution]

For the benefit of everybody. The "detecting" problem was caused by MTU size!

Default size is 1500, which is a hair too large. I changed it to 1492. Everything is running fine for the last week. No single disruption. 

I think this is ISP dependent. You can do a ping test to determine your MTU size. Just google it. 

[FURRYe38]

MTU size for most cable/fiber services is 1500. For DSL its 1492 or 1472.

We recommend contacting the ISP services to confirm that there MTU values ahouls be.

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@wharfedalemfm wrote:

For the benefit of everybody. The "detecting" problem was caused by MTU size!

Default size is 1500, which is a hair too large. I changed it to 1492. Everything is running fine for the last week. No single disruption. 

I think this is ISP dependent. You can do a ping test to determine your MTU size. Just google it. 

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