1st time post although long time follower of this site.
Background - I'm on outskirts of town on a 2.4 mile long BT ADSL1 line. Previously used HG612 in bridge mode to BT HH5A for routing/wireless. HG612 appeared to be very tolerant to line conditions and just worked, giving 7300 sync speed with snrm set to around 8dB to reduce errors. Happily ran for 3-4 months at a time without resync.
In January I noticed that broadband was freezing for up to 15 minutes at a time. This would happen 3-4 times a week, with no pattern regards time/usage etc. Snrm would drop to 3dB and errors go through roof. If left, line would recover by itself to original settings or a reboot would always work. Totally unrelated to these freezes, I noticed on HG612 stats that upstream bitswaps were being switched on at a constant rate of 30/min and would not recover until modem reset, only to switch on again after a few days.
Thinking that the HG612 was faulty, and reading about Zyxel routers on this site I invested £2.30!! in a VMG3925 B10B from ebay. With Rom-d cleared and latest firmware loaded, initially tried it as all in one but unimpressed by wireless coverage, so now just used as bridge to HH5A as before. After 10 days running in this mode the Zyxel does appear to work well on this line with a slightly higher sync speed and all errors are half those recorded by the HG612. And no freezes to date.
However, this morning I noted that the Zyxel also switched on constant upstream bitswaps just after midnight at the same rate 30/min. From other graphs, nothing else happened at that time.
While it does not appear to have any impact on speed, my question is - is this normal and to be expected? Or is there a fault somewhere causing this?
Attached are photos of the HG612 bitswap action from Feb and today on the VMG3925