Wireless Joint

I need help on changing the TTL, MTU and MSS values with WiFiX firmware. I’ve found that if I navigate to Firewall > Custom TTL it will allow me change to a few pre-defined TTL settings but not the TTL value I need. How do I change to TTL value of 100?

Also I’ve found that I can “Override MTU” if I navigate to Network > Interfaces > “Edit” wwan > Advanced Settings. Is this the correct place to change this value?

I’ve found nowhere to change the MSS value. Any help would be appreciated. Thanks.

MSS clamping and custom ttl settings will require entering custom firewall rules. That's a bit above my head right now, but you should maybe search around the OpenWrt site for documentation on those rules.

For TTL, go to Network-->Firewall-->Custom Firewall Rules (left of "Custom TTL Rules")

And enter your TTL modifications there. Here are my rules I use:

#start TTL rules Change all the values of "65" to any you choose, maybe 64, or 117 seems popular for Verizon
iptables -t mangle -I POSTROUTING -o wwan0 -j TTL --ttl-set 65
iptables -t mangle -I PREROUTING -i wwan0 -j TTL --ttl-set 65

#Start IPV6 TTL (hl) rules … usually onlyneeded for T-Mobile and sometimes Verizon, not recommended for ATT
#ip6tables -t mangle -I POSTROUTING -o wwan0 -j HL --hl-set 65
#ip6tables -t mangle -I PREROUTING -i wwan0 -j HL --hl-set 65
#end TTL rules


Delete the "#" from the lines where it says 'ip6tables' if you want to also use ipv6 "TTL" rules


The MTU Ive never played with

Didneywhorl wrote: Sat Aug 22, 2020 10:12 pm #Start IPV6 TTL (hl) rules … usually onlyneeded for T-Mobile and sometimes Verizon, not recommended for ATT

Didneywhorl, do you remember why modifying the Hop Limit field in IPv6 header wasn't recommended for ATT?

LoveMeSomeCALTE wrote: Tue Oct 05, 2021 1:17 pm Didneywhorl, do you remember why modifying the Hop Limit field in IPv6 header wasn't recommended for ATT?

Things change, but in general it wasn't necessary to overcome hotspot data limits, as ATT seemed to use APNs for data use channeling. Not really sure to be honest, outside of that.

Didneywhorl wrote: Sun Oct 10, 2021 3:38 pm Things change, but in general it wasn't necessary to overcome hotspot data limits, as ATT seemed to use APNs for data use channeling. Not really sure to be honest, outside of that.

Hey, Thank You for responding!

So, AFAYR, modifying the Hop Limit field in IPv6 header wasn't necessary but also didn't affect the plan/connection in any other way.

In other words, if I would use the same modem+router alternately with ATT and Tmo cards, the plan/connection would continue to work?

Didneywhorl wrote: Sun Oct 10, 2021 3:38 pm ATT seemed to use APNs for data use channeling

So ATT has `broadband` and `NXTGENPHONE` APNs - is there a specific one it uses for data use channeling?

Using TTL and HL mamgles on ATT, that match Tmo, doesn't seem to have a negative effect on the ATT connection.

I've not heard of any data count difference betwern the two, though the non BROADBAND APNs seem to require imei matching to account registered device.