Notices

After over 5 years of not using it I bought a new battery for my N810 but couldn't make Skype work like it was in the past. Does it still work today for the N810? Are there any changes to the settings I have to make?
Can anyone give any suggestions?

I use connection port 36855 and alternatively 80 and 443.

I would suggest 3 things .

1- continue dialogue on this topic under an n8x0 or diablo maemo 4 subforum . preferably a thread already there concerning skype...
Rather than continue it here.

2- if you do a reflash of latest diablo...
You should be able to simply sign in to your Skype account.
Fiddle around with it...and ..who knows what issues you will have.

3- The other option is to pm me and discuss it further.

Skype has stopped working in WP, Symbian and MeeGo. Question is, is there any way to fix the apps in order to connect to Microsoft's servers?

How many folks are running around using WP, Meego, and Symbian?
And out of those numbers in each of those OS's...how many of those folks are knowledgeable enough to fix their variant of Skype?
And that is saying that the past "fixes" to get Skype functional on those specific OS's is the same kind of fixable problem as the past issues...
Which in point of fact...they aren't.
Skype has moved deliberately so far away from being "fixable" for Meego, WP, and Symbian it is now an impossibility to fix.
It is a combination of dropping of support for old os's and increased expectation from aging versions that are heading out the door..marked for discontinuation...
Where once upon a time it was fixable for the OS's in question...
It isn't any longer.
Also to add to the issue is that..
Unlike other services such as Telegram, which has a much more open policy and IF there are folks in said community that can juggle work -arounds for it...then it can be kept going for a while..on said OS's...
But more closed progs such as whatsapp , Facebook, Skype... etc...
When they make changes they are not easily worked around to get them to function again..
And to make the issue worse still..
Said progs like Skype, Whatsapp , and Facebook on a consistently regular basis change their progs so significantly ...in some cases multiple times in a year...effectively making any fix temporary ...
So.. whoever does work on "fixes" is doing so perpetually...
In essence you need a couple people working on a "fix", or a small team to do it and keep maintenance of said programs..

It just isn't feasible.
The n900 was probably and compared to the other mentioned devices.. Has still greater numbers of savvy users, power users, and cunning folks that can " fix" lots of issues...but even still...
See any running Facebook, or Whatsapp app for the n900?
Skype is so much more difficult to attempt to fix.

If anything we need a implementation of tox for Maemo rather than fix a Skype for Maemo5; a Skype which I wont even use on desktop Linux anymore. Even better a full edition of Briar which uses tox to communicate over internet.
Skype, Facebook(and Whatsapp a Facebook company), and all of google are the enemies of freedom, friends of state power, and these corporations stand against the spirit which still enervates the Maemo movement and the whole free software, ethical hacking, and privacy movements.
https://en.wikipedia.org/wiki/Tox_(protocol)
Tox is a secure encrypted FOSS IM, VOIP, and videoconferencing protocol.
Briar adds offline WiFi and Bluetooth alternative 'sneakernet' routing until a network connection becomes possible as well as usenet like discussion groups as well as tox personal messaging.
there is already tox plugins available for Pidgin and since it is from 2013 likely will work with the libs we have.
https://github.com/jin-eld/tox-prpl

My Synology NAS has built in chat server which allows me to get off whatsapp and skype etc. I host the server and control access with end to end encryption possible. Works great now, which was not the case a year ago when i first tried it, they had a few bugs to iron out. Only problem i have is i am on a 5G cellular internet access connection which has significant NAT in place which seems cant be avoided, so while my Jolla 1 can connect using the android app or directly using the webserver in the NAS, the N900 is again lacking certificates and browser power to use the webserver side of things. which is a bit of a shame....

ssh(tunnel) or vpn out to a server and dmz everything into the tunnel; nat fixed.

Thanks Biketool, The problem is the LTE 5G modem from the ISP gives me a 192.x.x.x IP address but my real external IP is 37.x.x.x but my router cannot see it, so services like DDNS don't function. This double NAT situation appears to the price you pay for high speed LTE based internet. I've had Wimax connections (100mb/s) before and a quick call to get NAT switched off (no need to pay for static IP) solved this issue, but Wimax is not available at this address. But from what I have read with this LTE/5G technology NAT can only be resolved on IPV6 not on IPV4, and then only at a price. Getting a static IP doesn't solve the issue, as it did on cable/fibre based systems.
I think I understand your suggestion about VPN out to a server but it brings a couple of issues, security if using a external server "service", which defeats the object really of a secure chat server. But also speed, if I use my own external server and VPN to that, I have no where with 250mb/s connection to place the server. If you still think your proposal will work I would be happy to try it if you can clarify more.

It is possible to have another interface device, which pipelines transparently through all of the NAT crap, like you do when you use a VPN.
I am too rusty after a good number of years and would have to trial and error it, but just look up a good documentation of working with routing tables and you will be hanging your network nude to the world before you know it.
If you want to take it easy though just use one of the Maemo5 openVPN clients on the repos and pipe through a free protonVPN account or set up a VPN server or SSH tunnel on a non-NATed machine somewhere.
some low effort minimal review searching came up on DDG
https://medium.com/botfuel/how-to-ex...t-c31532d741cc
(edit)
This should give you what you need to set up a network bridge
https://www.linuxjournal.com/article/10929

I will take a look! Many thanks.