Scrapy爬虫请求start_urls后立即关闭的问题排查

我编写了如下Scrapy爬虫：

from scrapy.spiders import CrawlSpider, Rule
from scrapy.linkextractors import LinkExtractor

class CrawlingSpider(CrawlSpider):
    name = "tb_crawler"

    start_urls = ["https://www.bank1saar.de/startseite.html"]
    allowed_domains = ["bank1saar.de"]

    rules = (
        Rule(LinkExtractor(), callback='parse_item', follow=True), 
    )

    def parse_item(self, response):
        pass

爬虫未抓取任何内容就关闭，运行日志如下：

(tb_crawler) C:\Analysen\scrapy\website_screener\tb_web_crawler>scrapy crawl tb_crawler
2023-06-05 13:37:54 [scrapy.utils.log] INFO: Scrapy 2.9.0 started (bot: tb_web_crawler)
2023-06-05 13:37:54 [scrapy.utils.log] INFO: Versions: lxml 4.9.2.0, libxml2 2.10.4, cssselect 1.2.0, parsel 1.8.1, w3lib 2.1.1, Twisted 22.10.0, Python 3.11.3 | packaged by conda-forge | (main, Apr  6 2023, 08:50:54) [MSC v.1934 64 bit (AMD64)], pyOpenSSL 23.2.0 (OpenSSL 3.1.1 30 May 2023), cryptography 41.0.0, Platform Windows-10-10.0.19042-SP0
2023-06-05 13:37:54 [scrapy.crawler] INFO: Overridden settings:
{'BOT_NAME': 'tb_web_crawler',
 'FEED_EXPORT_ENCODING': 'utf-8',
 'NEWSPIDER_MODULE': 'tb_web_crawler.spiders',
 'REQUEST_FINGERPRINTER_IMPLEMENTATION': '2.7',
 'SPIDER_MODULES': ['tb_web_crawler.spiders'],
 'TWISTED_REACTOR': 'twisted.internet.asyncioreactor.AsyncioSelectorReactor',
 'USER_AGENT': 'Mozilla/5.0 (iPad; CPU OS 12_2 like Mac OS X) '
               'AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148'}
2023-06-05 13:37:54 [asyncio] DEBUG: Using selector: SelectSelector
2023-06-05 13:37:54 [scrapy.utils.log] DEBUG: Using reactor: twisted.internet.asyncioreactor.AsyncioSelectorReactor
2023-06-05 13:37:54 [scrapy.utils.log] DEBUG: Using asyncio event loop: asyncio.windows_events._WindowsSelectorEventLoop
2023-06-05 13:37:54 [scrapy.extensions.telnet] INFO: Telnet Password: beaf19279aa4a320
2023-06-05 13:37:54 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.logstats.LogStats']
2023-06-05 13:37:54 [scrapy.middleware] INFO: Enabled downloader middlewares:
['scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
 'scrapy.downloadermiddlewares.retry.RetryMiddleware',
 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
 'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
 'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2023-06-05 13:37:54 [scrapy.middleware] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
 'scrapy.spidermiddlewares.referer.RefererMiddleware',
 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
 'scrapy.spidermiddlewares.depth.DepthMiddleware']
2023-06-05 13:37:54 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2023-06-05 13:37:54 [scrapy.core.engine] INFO: Spider opened
2023-06-05 13:37:55 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2023-06-05 13:37:55 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023
2023-06-05 13:37:55 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://www.bank1saar.de/startseite.html> (referer: None)
2023-06-05 13:37:55 [scrapy.core.engine] INFO: Closing spider (finished)
2023-06-05 13:37:55 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 297,
 'downloader/request_count': 1,
 'downloader/request_method_count/GET': 1,
 'downloader/response_bytes': 7973,
 'downloader/response_count': 1,
 'downloader/response_status_count/200': 1,
 'elapsed_time_seconds': 0.217698,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2023, 6, 5, 11, 37, 55, 315335),
 'log_count/DEBUG': 4,
 'log_count/INFO': 10,
 'response_received_count': 1,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'start_time': datetime.datetime(2023, 6, 5, 11, 37, 55, 97637)}
2023-06-05 13:37:55 [scrapy.core.engine] INFO: Spider closed (finished)

爬虫启动后立即停止，日志显示INFO: Crawled 0 pages (at 0 pages/min)和INFO: Closing spider (finished)，未进行深度爬取。

更换为以下配置时爬虫可正常运行：

start_urls = ["https://www.oldenburg.de/startseite.html"]
allowed_domains = ["oldenburg.de"]

更新：
爬虫偶尔能正常运行，是不是大概率被目标站点拦截了？恳请提供排查建议。

内容的提问来源于stack exchange，提问作者PParker