I love my Beryl AX in no small part because of the policy based routing in 4.8.3 of the firmware. But often I prefer the size, albeit more modest capabilities, of the Mango, which is still at the 4.3 level of the firmware. So I thought I would report on moving Mango to vanilla OpenWRT. to replicate that.
If there is interest I will do a more detailed writeup, but I thought I would point out a few things.
I installed 25.12.1 (the current OpenWRT version), which includes an integrated imagebuilder that works really well. I installed wireguard, travelmate and pbr for the core travel router needs, and also nano and adblock. Deleted ppp but kept ipv6. Then rebuilt the firmware so I had a compact, slimmed down version.
I didn't install openvpn, although 25.12 allows dco and might be as capable as wireguard, but I've kind of moved on. I have about 9mb of room left for apps.
Two things had me tearing my hair out. One is that pbr is hard-coded to require a wan interface to start. You have to manually edit the .conf file to change the uplink interface to wwan or trm_wwan to get it to start. The other was a difficult time having both wireguard interfaces operating well; that turned out to be a server side allowed-ip problem. It does take time for the scripts to settle down.
I'm seeing speedtest.net tests of between 12/12 and 17/20 for throughput from a laptop connected over wifi to the Mango, with the Mango uplinked to a wifi hotspot provided by a cell phone transatlantically to a capable Wireguard server. (Hard test, right?) But the Mango is not being maxed out, so these speeds are likely limited by things other than the Mango.
I know now a lot more about OpenWRT and its awesome flexibility, but man, the Gl-Inet GUI is so much easier to deal with.
EDIT: For a lark, I hooked up a Beryl MT1300 (so, dual-core 7621, slightly higher clock speed) with stock 4.3.25 on the same 2.4 band, and got speedtest results of about 30/20 over the same hotspot to the same wireguard server and the same result not using wireguard. About 50/30 using 2.4 band for the uplink and 5 for the laptop. So the Beryl on stock maxes out the connection at 30/20 that produces 12-17 up and 12-20 down on the single core 7628n with the current Openwrt.