Hi,
I have a SIM card for 4G internet access at my secondary residence, which I use in my 4G router (Huawei). Everything was working fine, but the provider (NOS) must have had a noticable increase in traffic over the last months, so I changed the SIM card with one of the competition (Vodafone). These are pre-paid cards, costing 30 Euro for 30 days. I know there are cheaper deals, but they come with a 2 year fidelity contract, which I am not interested in, because I expect fiber to be available in some not so far away future.
So my problem is that with the new Vodafone SIM, ocasionally, the internet does not work. I know that because all the surveilance cameras get offline. After 2-3 days, they become active again, without any intervention.
Today I was there when it happend. Unfortunately I did not have much time, but what I discovered is that the router changed the DHCP settings from 192.168.3.X to 192.168.4.X! Also, it seems that the WAN I got assigned is actually from 192.168.3.X subnet. This explains why the DHCP server started to hand out IP's in a different subnet than the one I originally configured.
Is this even possible? I know that mobile internet providers use NAT instead of giving an individual IP address, but can they be using private IP addresses instead of public ones?
I think that this is what renders my network useless: because I am using mainly fixed IP addresses (settop boxes, access points, etc.), if the router/gateway is in a different subnet, nothing works.
Also, I think it gets back to normal after a few days, when the lease of the WAN IP terminates and I get assigned a WAN IP in the a different range, which causes the router to switch the DHCP server back to giving out 192.168.3.X addresses, as it should.
But this is weird: how does the router "remember" the former IP settings? And how does it adjust the settings automatically?
Any ideas on what is going on? I don't want to have to reconfigure all devices in my network and I have no guarantees that Vodafone is not using any other subnet within 192.168.X.X.
Thanks,
Vitor