Question Issue with 2 x Pepwave routers via Ethernet connections

[Neal]

I'm running 2 x Pepwave BR1 Pro 5G routers. Pepwave 2 has an ethernet connected to its LAN port, this ethernet is going into Pepwave 1's WAN port. This allows me to take the Internet connections and use them on Pepwave 1 (WAN node).

As I've learned in my house, wired connections are best if you can use them. I have a 1 Gig FIOS service into my house and WiFi 6 is only giving me 1/3rd of that (something I may fix later with something other than Netgear crap). Regardless, this is the theme on networking these days, wired if you can, then wireless. As I have ethernet run from the AV box where my pepwave is to my dinette I put an unmanaged fanless switch in there to connect my Synology NAS (network attached storage) and two laptops (mac and windows). Giving me an ideal setup so I have no speed loss due to WiFi and max speed (1 Gig) between the NAS and computers.

All should work peachy right? Well, something is going very wrong. When Pepwave 1 is using it's WAN source (AT&T) everything works fine on all systems. I can download a 500 MB file with no problem. Now if I change Pepwave 1 to use Pepwave 2 as it's WAN source, the download will start and then fail about 5 MB into it (network failure or some message to that effect). I tried both Google Chrome and FireFox wondering if it was a browser issue. Same problem on both.

If I use WiFi and disable the ethernet adapter, all works perfect. So this is not an issue with cabling, something in the networking side is not jiving. I tried pass through options but nothing there worked to solve this problem. I realize this is a double router situation, double NAT but is not an issue when all done over WiFi, only cabled connectivity.

Any of you geeks out there have any suggestions as to what's going on and why connectivity is unstable or failing when feeding off of Pepwave 2?

 

[Neal]

I may have stumbled upon the problem. MTU size. I did some testing and my MTU needs to be down to 1300 to avoid fragmentation. So far this tests good.

MTU Size: What Is It and What Should It Be Set To? - Home Network Geek

MTU size is the maximum packet size that can be transmitted over your network. Changing it is an easy way of optimizing your home network's performance.

homenetworkgeek.com

I'll try 1328 per this article:

How to determine the optimal MTU and MSS size

Setting the correct MTU size can make a difference in optimizing your network speeds. The MTU size, or Maximum Transmission Unit Size, is the largest physical packet size, measured in bytes, that a network can transmit. Any messages larger than the MTU are divided into smaller packets before...

forum.peplink.com

Good info:

https://knowhow.peplink.ninja/kb/what-are-the-default-wan-mtu-sizes-used-by-peplink-routers/

 

[Neal]

Sent an email to 5GStore support to see what they say. MTU is not it.

 

[Scotttkd2]

Hi Neal, I am going back through pepwave threads digging out info, did you get a resolution to this issue??

 

[Neal]

It is/was something to do with Verizon on the 2nd pepwave. If I put AT&T in that pepwave there's no problem. I have a few more things to try but putting Verizon in the primary pepwave resolves it.

 

[Scotttkd2]

Wow, that is a little weird.

 

[Tnedator]

It is/was something to do with Verizon on the 2nd pepwave. If I put AT&T in that pepwave there's no problem. I have a few more things to try but putting Verizon in the primary pepwave resolves it.

Any chance any of your sim settings (verizon sim in 2nd Pep) such as minimum signal strength or other auto health checks were set too high/tight, and it was trying to switch off that sim due to weak signal, high latency, etc.?

 

[Neal]

Any chance any of your sim settings (verizon sim in 2nd Pep) such as minimum signal strength or other auto health checks were set too high/tight, and it was trying to switch off that sim due to weak signal, high latency, etc.?

I have an extensive back and forth with Peplink support and 5GStore monitoring the convo. I think because of wherever Peplink is (overseas) they can't reproduce the issue as they don't have the sim/plan whatever. The final suggestion was trying a TTL setting on Pep2 and I don't remember if I tried that but as the coach was in storage I threw in the towel and will tinker when I hit the road. The simple fix is swap the sims. The settings are default/stock, I don't tweak anything. I think it's some TTL issue with the two pepwaves connected. Computer => Pep1 => Pep2 (active wan) and Verizon didn't like it.

 

[Neal]

Follow up - I did set TTL to 65 on Pep 2 and have had no issues with Verizon. I've been running pure ethernet (non Wi-Fi) from my computer for two weeks no issue.

 

[Tnedator]

Follow up - I did set TTL to 65 on Pep 2 and have had no issues with Verizon. I've been running pure ethernet (non Wi-Fi) from my computer for two weeks no issue.

Glad this is sorted. I'm about to place a pre-order on a BR2 + order a BR1 Pro 5G to get three cell modems for bonding or failover.

Go big or go home.