Steve,
I think I did understand, but I cannot know what this hotel's problem is to connect most of their guests to the internet. What I was trying to do is to collect for you a semi-systematic list of checks that have a chance of uncovering the problem. But you really need to inspect the results of the checks I suggested to you

.
Example: if resolv.conf does not contain the URL of a DNS (server), your Firefox browser will most probably tell you after a little while:
Server not found. But then, if instead ping does a successful "roundtrip" to the URL and back with the
numerical equivalent of the address, you know that the problem was the missing DNS. To do this test, you need to be connected briefly to the internet and use nslookup, which converts the given URL to its numerical equivalent.
Example: URL= forum.celestialmatters.org
then executing nslookup
> nslookup forum.celestialmatters.org
returns
Non-authoritative answer:
Name: forum.celestialmatters.org
Address: 152.19.134.41
then you do
> ping 152.19.134.41
PING 152.19.134.41 (152.19.134.41) 56(84) bytes of data.
64 bytes from 152.19.134.41: icmp_seq=1 ttl=46 time=122 ms
64 bytes from 152.19.134.41: icmp_seq=2 ttl=46 time=129 ms
64 bytes from 152.19.134.41: icmp_seq=3 ttl=46 time=125 ms
64 bytes from 152.19.134.41: icmp_seq=4 ttl=46 time=123 ms
64 bytes from 152.19.134.41: icmp_seq=5 ttl=46 time=122 ms
...
which looks perfect.
Here is a URL from a Google DNS server that you may add by hand into resolv.conf
nameserver 8.8.8.8
Good luck
Fridger
PS: my experience with failed connections over many many years => either it's a bug in the Network Manager or it's something wrong in the resolv.conf file!