Hello,
yes I use Winbox to connect.
I will use your mentioned way later - /system reset capsmode and then report back.
Thank you very much for your support.
Use terminal on CAPS and execute:
/system reset-configuration caps-mode=yes
Thank you very much for your support.
That helped, and I can now connect to the Wi-Fi (2.4 GHz and 5 GHz) with my smartphone.
The new project will be to introduce VLANs. I was thinking of 3 VLANs (home, IoT, guest). Does that make sense?
Yes, it does, mostly. However for a domestic network, the home vLAN can be superfluous. If you think of the separation required between n different sub networks, you can achieve it with n-1 vLANs. Remember that the default or native vLAN is vLANid=1. Only do the home sub network as a vLAN if you have a positive reason to do it. And if you are new to vLANs, just start by implementing one of them rather than doing everything at once.
Yet the general recommendation here is once you go VLAN, don't use 1.
Just don't.
Too much possible issues with other gear or even MT gear, so best to avoid it completely.
I am not suggesting setting up a vLANid=1, I am suggesting don't do a vLAN for home. For domestic network, leave the native vLAN be until and unless you find a specific reason to do it. If you don't touch the native network, it won't have problems with other kit which were not there before vLANs.
A lot of our problems here from people unfamiliar with vLANs [generally domestic networks] arises from overwhelming people with too much instruction and rushing them into an all or nothing implementation. I have absolutely no problem from my native vLAN, I have done no vLAN configuration on it, but it coesists with the other vLANs I have implemented.
I agree that VLANs can be a high step to cross - if one doesn't have at least basic knowledge about L2 networking.
OTOH my opinion is that mixing "no VLAN for home" with VLANs does add to confusion because in this case the "no VLAN" part doesn't fit the VLAN picture (and adding the VID 1 to the picture it becomes a nice confusion).
So my suggestion would be: go all VLAN (and stay away from VID 1). Do it on a spare device (or two if available) and once things "click together" put it into operations (and add other VLANs as needed/wanted, it's pretty easy to add VLANs once everything is set up for VLANs correctly).
@DuctView
When you do not set pvid, it is actually 1 since that's default value for VLAN.
Search a bit on WWW.
It's not only here that it is recommended not to use VLAN 1 if you use VLAN in your setup.
You'll find plenty of examples, even from Cisco.
That is known art.
It works fine here. The security argument does not really apply for a domestic network. And I don't think we should be telling these scary partial stories, which effectively amount to half truths. We should be saying something along the lines "If you are mixing with kit which uses a vLANid other than 1 for its native LAN, you may need to implement your basic LAN as a vLAN" vLANs are already too inaccessible and I fundamentally disagree with making the barrier to adoption higher.
Most peoples' spare device or 2 comes out of a box which contains stuff for a reason. I was fortunate to get a Mikrotik ISP ARM based router from a neighbour after he and I ditched the wireless ISP and got fibre. The ISP router I had was not up to it.
@Mifoerst
Just in case:
There is not really-really a need for VLANs in a simple home setup, if two/three separate groups are all that is needed it is possible to do it without VLANs, JFYI:
https://tangentsoft.com/mikrotik/wiki?name=Isolated%20Guest%20WiFi%20Sans%20VLANs
A router and 2 access points is outside the definition of simple if you want a guest network for the whole system rather than a guest 'port' per access point. This is exactly the strike in point for 'My First vLAN' and is an increasingly common home network scenario. I see no need to vLAN the basic LAN. Even if you add an IoT vLAN [again, increasingly common], I see no need.
Yes, this is clear enough as a basic howto, but it says "Although the master interface (wifi2) is on the router’s main bridge, it is important that this new slave not be on any bridge." So now we hit the problem that we need a new paradigm if we want to run the guest network seamlessly on both 2GHz and 5GHz. We could use the CAT5TV approach of adding a software bridge, but this is a dead end for more than 1 AP, where CAPsMAN and a vLAN is the way to go.
Re The 12 rules of Mikrotik club, it says Virtual LAN identifier or tag that is used to distinguish VLANs. Must be equal for all computers that belong to the same VLAN. BUT DO NOT USE explicitly VLAN id=1, imagine that ONLY 2..4094 are valid, unless you really know what you are doing. I always took this to mean that if you left the implicit vLANid=1 stuff alone and didn't try to limit, extend or otherwise alter the native vLAN, it shouldn't be a problem. I do understand that this heuristic might be limited to a Mikrotik monoculture and that works very well for me, even with some Netgear unmanaged network thrown in.
Exactly. 
The whole point is that in Mikrotik devices (in default RouterOS configurations) there are some settings related to VLAN1 that are normally not shown (unless you use verbose switch of export).
When you explicitly set pvid=1 or vlan-id=1 in some parts of your custom configuration these may (or may not) create a conflict of some kind with these (hidden) settings and thus create a mis-configuration.
When this happens, it is particularly difficult to find which settings are conflicting and how exactly such conflicts affect the way the device works.
Experienced people with a very deep knowledge of both the theory of VLANs and practical Mikrotik implementation of them can actually use VLAN1 (because they do know the consequences of the settings they change), but for most "common" users avoiding using VLAN1 explicitly in your configuration is the simplest way to make sure that such conflicts cannot happen.