I followed the tutorial on the documentation with the Huawei E303 modem— everything works great, I can stand up a new connection, hit the internet, and tunnel back with spacebridge. (I’m using the stock configs from your documentation for pppd)
The problem is that the connection seems to go idle after about 15 seconds of non-use. So, if I try to connect with spacebridge, it basically sits waiting until it times out OR I do something on the device to re-establish the connection, like ping on the cell interface.
I can avoid the issue by having ping run continuously in the background on the device, but that feels hacky (and expensive in terms of data use).
If I issue a ping after the connection has gone idle, I can see that the first ping response takes significantly longer, around 2s, before dropping back down to around ~250ms… so something is obviously happening where the connection to the cell network is being stood back up.
Any tips on pppd configuration or where/how to start debugging so I can keep the connection alive without having to resort to running ping continuously?