You can install the package openssh-sftp I believe and then connect via filezilla to your router via sftp.

Or maybe you can use curl <url> --OUTPUT package.ipk and then follow the commands.

Also running 3.208 here and I can confirm this firmware and the newer busybox update works very stable, no more dhcp dropping here.

The only issue I found was mwan3 causing sometimes problems with dropping aswell especially on different interfaces, I was searching as for why in the issue tracker on openwrt.

As from what I understand is that mwan3 sometimes chooses the wrong wan interface especially when the configuration is not properly set.

What I mean with not properly is that each interface such as vlan interface for example or a isolated routed AP as interface, shares metric 0 or 10, this could cause unpredictfull behaviour, if I would fill in the gateway in one of the interfaces luci shows under stats the vlan as wan, the issue got solved when I made the metrics invidual different for each, I noticed far more less dropping from both stubby and vlans by doing this change.

Im not sure if theres any upstream patches for mwan3 for this, but it could be great.