I've wanted to play with multi-WAN routing setups in my homelab for awhile. I thought about buying Starlink, but it's a bit pricey as a purely backup solution, and I'm in a situation where my primary internet is very reliable for about the same price. So I settled for LTE backup. I looked around for awhile, trying to decide what the right solution is for me. I really wanted to pass through the IPv4 address and IPv6 prefix from the ISP through to my OPNsense router, since I don't want to deal with triple-NAT and dual layer firewall. A lot of LTE hotspots, even those that support wired Ethernet, still act as firewall routers, and I didn't want that hassle.

I ended up selecting the Mikrotik SXT US Kit, which includes a US band LTE modem, decently directional antenna, wired Ethernet with PoE, and RouterOS. RouterOS is .... dense with configuration options, and I'm not that good at managing it, but it's supposed to be able to do a pure passthrough of the LTE modem to an interface without interfering with the network at all.

I was able to configure this in RouterOS eventually. I'm happy with the hardware so far. I stuck it in a window facing roughly the direction of my nearest T-mobile tower and it just worked. I'm sure if I was more on the fringes of cell service I would have needed an actual pole and to actually aim it.

I tested with a temporary server connected directly to the modem and was able to successfully receive inbound connections to my IPv6 address, although I've heard T-mobile blocks ICMP (ping) packets. HTTP inbound worked fine. There's sometimes a huge latency (~1sec) in getting the first packet through, followed by much more reasonable latency. So, yes, you should be able to host games on this without NAT issues if your game supports native IPv6 and you configure your firewall appropriately.

Blog post with the RouterOS commands:
https://www.apalrd.net/posts/2022/net...

I made a big oof in the video and used fast.t-mobile.net instead of fast.t-mobile.com. oops.

Eventually I'll release a video on setting up failover routing in OPNsense using this as the secondary connection. Stay tuned for that adventure.

I'm ready for you RouterOS experts to tell me what I did wrong in the comments.

My Discord server:
  / discord  

If you find my content useful and would like to support me, feel free to here: https://ko-fi.com/apalrd

Timestamps:
00:00 - Hardware Overview
02:37 - RouterOS Setup
07:46 - SLAAC with IPv6 rant
08:49 - OPNsense Basic Setup
10:45 - Conclusions

#LTE
#Mikrotik
#TMobile
#OPNsense